[ANCHOR-220] Refactor README (#1064)

### Description
- Fix, clean up and improve the `How to Contribute` section 
- Add How to set up development environment
- Add Git guidelines
- Add repository directory structure
- Remove outdated contents

README.md

@@ -1 +1 @@
-./docs/00 - Stellar Anchor Platform.md
+./docs/README.md

docs/01 - Contributing/A - Development Environment.md

@@ -0,0 +1,208 @@
+# How to set up the development environment
+
+<!-- TOC -->
+
+* [How to set up the development environment](#how-to-set-up-the-development-environment)
+    * [Install JDK 11](#install-jdk-11)
+    * [Checkout the Project](#checkout-the-project)
+    * [Set up `docker`](#set-up-docker)
+    * [Set up your hosts file](#set-up-your-hosts-file)
+    * [Build the Project with Gradle](#build-the-project-with-gradle)
+        * [Clean](#clean)
+        * [Build](#build)
+        * [Running Unit Tests](#running-unit-tests)
+    * [Set up the Git Hooks](#set-up-the-git-hooks)
+* [Set up the Development Environment with IntelliJ IDEA](#set-up-the-development-environment-with-intellij-idea)
+    * [Configuring Gradle on IntelliJ IDEA](#configuring-gradle-on-intellij-idea)
+    * [Run Configurations](#run-configurations)
+        * [Example: Debug the Platform Server](#example-debug-the-platform-server)
+        * [Example: Debug the Junit or the End-to-End Tests](#example-debug-the-junit-or-the-end-to-end-tests)
+    * [Running the Tests From Gradle in IntelliJ](#running-the-tests-from-gradle-in-intellij)
+
+<!-- TOC -->
+
+## Install JDK 11
+
+Before you start, please make sure you
+have [JDK-11](https://www.oracle.com/java/technologies/javase-jdk11-downloads.html) installed on your machine.
+
+To check if you have it installed, run:
+
+```shell
+java -version
+```
+
+## Checkout the Project
+
+To check out the project, run:
+
+```shell
+git clone [email protected]:stellar/java-stellar-anchor-sdk.git 
+```
+
+or
+
+```shell
+git clone https://github.com/stellar/java-stellar-anchor-sdk.git
+```
+
+## Set up `docker`
+
+Please make sure you have `docker` installed on your machine. If you don't, please follow the instructions on
+the [docker website](https://docs.docker.com/get-docker/).
+
+Docker version 23.0.0 or higher is recommended. To check your docker version, run:
+
+```shell
+docker --version
+```
+
+You should see something like:
+
+```shell
+Docker version 23.0.5, build bc4487a
+```
+
+## Set up your hosts file
+
+On macOS and Linux, you need to add the following entries to your `/etc/hosts` file. And on Windows, you need to add the
+following entries to your `C:\Windows\System32\Drivers\etc\hosts` file.
+
+These entries are needed to successfully run integration tests and end-2-end tests for the docker containers to
+communicate with each other.
+
+```shell
+127.0.0.1 db
+127.0.0.1 zookeeper
+127.0.0.1 kafka
+127.0.0.1 sep24-reference-ui
+127.0.0.1 reference-server
+127.0.0.1 wallet-server
+127.0.0.1 platform
+127.0.0.1 host.docker.internal
+```
+
+## Build the Project with Gradle
+
+### Clean
+
+`./gradlew clean`
+
+### Build
+
+Buile all projects: `./gradlew build`
+
+Build a subproject: `./gradlew :[subproject]:build`
+
+Build the Spring Boot application: `./gradlew bootJar`
+
+### Running Unit Tests
+
+Run all tests: `./gradlew test`
+
+Run subproject tests: `./gradlew :[subproject]:test`
+
+## Set up the Git Hooks
+
+In order to have consistent code style, we use [Google Java Format](https://github.com/google/google-java-format) to
+format the code, and [ktfmt](https://github.com/facebook/ktfmt) to format Kotlin code.
+Before each commit, you should run the git hook to format the code. We have a script that will set up the git hooks for
+you. To install it, run:
+
+```shell
+./gradlew updateGitHook
+```
+
+The gradle `updateGitHook` task will install the git hooks for you. You should see `spotlessCheck` and `spotlessApply`
+being executed when you commit your code.
+
+# Set up the Development Environment with IntelliJ IDEA
+
+The project is mostly developed with IntelliJ, therefore we will only cover the project configuration for that IDE.
+
+## Configuring Gradle on IntelliJ IDEA
+
+1. Clone the repository:
+
+    ```shell
+    git clone [email protected]:stellar/java-stellar-anchor-sdk.git
+    ```
+2. Install IntelliJ
+3. Install and configure `google-java-format`
+    1. File -> Settings -> Plugins -> Marketplace -> Search for `google-java-format` -> Install
+    2. File -> Settings -> google-java-format -> Check `Enable google-java-format` and
+       choose `Default Google Java Style` -> Apply
+4. Install and configure `ktfmt`
+    1. File -> Settings -> Plugins -> Marketplace -> Search for `ktfmt` -> Install
+    2. File -> Settings -> Editor -> ktfmt -> Check `Enable ktfmt` and choose `Google (internal)` -> Apply
+5. Use IntelliJ to open as a Gradle project:
+    1. Launch IntelliJ
+    2. File -> Open, choose the folder `java-stellar-anchor-sdk` where you cloned the repository.
+    3. When asked, choose `Open as Project`.
+    4. IntelliJ will parse Gradle buildscript `build.gradle.kts` file and configure the project accordingly.
+6. Configure Gradle to build & run using IntelliJ IDEA:
+    1. Go to `Preferences -> Build, Execution, Deployment -> Build Tools -> Gradle`.
+    2. Configure `Build and run using` to IntellliJ IDEA.
+    3. Configure `Run tests using` to IntellliJ IDEA.
+
+   ![configure-intellij-gradle.png](/docs/resources/img/configure-intellij-gradle.png)
+
+7. Refresh the project using Gradle's new configuration:
+    1. Open Gradle tool window: `View -> Tool Windows -> Gradle`
+    2. Click the `Reload All Gradle Projects` button.
+
+   ![gradle-reload-all.png](/docs/resources/img/gradle-reload-all.png)
+
+## Run Configurations
+
+Several IntelliJ run configurations are provided to make it easier to run the project.
+
+- `Docker - Run Dev Stack - Zookeeper, Kafka, DB`: runs the development stack locally, using `docker-compose`.
+- `Run - All Servers - with Docker`: runs all the servers locally, using `docker-compose`.
+- `Run - All Servers - no Docker`: runs all the servers locally, without running `docker-compose`.
+- `Run - Sep Server - no Docker`: runs the SEP server locally, without running `docker-compose`.
+- `Run - Platform Server - no Docker`: runs the Platform server locally, without running `docker-compose`.
+- `Run - Event Processing Server - no Docker`: runs the Event Processing server locally, without
+  running `docker-compose`.
+- `Run - Java Reference Server - no Docker`: runs the Java Reference server locally, without running `docker-compose`.
+- `Run - Kotlin Reference Server - no Docker`: runs the Kotlin Reference server locally, without
+  running `docker-compose`.
+
+The following run configurations are provided to run integration and end-2-end tests
+
+- `Test - Kotlin Reference Server - no Docker`: runs the Kotlin Reference server locally, without
+  running `docker-compose`.
+- `Test - End2End Test - no fullstack`: runs the end-2-end tests locally, without running `docker-compose`.
+- `Test - End2End Test - with fullstack`: runs the end-2-end tests locally, with running `docker-compose`.
+- `Test - Integration Test - no fullstack`: runs the integration tests locally, without running `docker-compose`.
+- `Test - Integration Test - with fullstack`: runs the integration tests locally, with running `docker-compose`.
+
+### Example: Debug the Platform Server
+
+If you would like to debug the Platform server, you can do so by running the
+
+- Make sure `docker` and `docker-compose` is available on your local machine.
+- Run `Docker - Run Dev Stack - Zookeeper, Kafka, DB` to start the development stack.
+- Run `Run - Sep Server - no Docker` to start the SEP server.
+- Debug `Run - Platform Server - no Docker` to start debugging the Platform server.
+
+### Example: Debug the Junit or the End-to-End Tests
+
+If you would like to debug the unit tests or the end-to-end tests
+
+- Make sure `docker` and `docker-compose` is available on your local machine.
+- Run or Debug `Run - All Servers - with Docker`
+- Debug `Test - End2End Test - no fullstack` or `Test - Integration Test - no fullstack`
+
+## Running the Tests From Gradle in IntelliJ
+
+To make sure your configuration worked, please make sure you can run all the tests successfully from the IDE:
+
+1. Open the Gradle tool window: `View -> Tool Windows -> Gradle`.
+2. Navigate to the all tests option: `Tasks -> verification -> test`.
+3. Right-click it and select the `run` or `debug` option:
+   ![running-the-tests.png](/docs/resources/img/running-the-tests.png)
+
+__Note__: You may need to check there is no active docker containers running on your machine from the previous debug
+sessions. If there are, please stop and delete them. 
+

docs/01 - Contributing/B - Git Guidelines.md

@@ -0,0 +1,49 @@
+# Git Guidelines
+
+Please follow the guidelines below when contributing to this project via Git and pull requests.
+
+<!-- TOC -->
+* [Git Guidelines](#git-guidelines)
+  * [Git Commit Messages](#git-commit-messages)
+  * [Pull Request Style](#pull-request-style)
+  * [Our Git workflow](#our-git-workflow)
+<!-- TOC -->
+
+## Git Commit Messages
+
+Write your commit message in the imperative: `"Fix bug"` and not `"Fixed bug"` or `"Fixes bug."`  This convention
+matches up with commit messages generated by commands like git merge and git revert.
+
+Example:
+
+```text
+Fix issue where Foo is handled as Bar.
+
+Further paragraphs come after blank lines.
+
+- Bullet points are okay, too
+- Typically a hyphen or asterisk is used for the bullet, and bullets are wrapped by spaces before and after each bullet block.
+
+If the commit relates to an issue, add a reference(s) to them at the bottom, like so:
+
+Resolve: #123
+```
+
+## Pull Request Style
+
+- Push the commits to your forked repository and create a pull request to the `develop` branch of this repository.
+- When starting a pull request, it's recommended to start it as draft, so that it's clear that it's still a work in
+  progress.
+- When the pull request is ready for review, remove the draft status and optionally post the message to
+  the `#ptal-anchor-eng` Slack channel.
+- If possible, please prefix the pull request title with Jira ticket number, like:
+    - `[ANCHOR-100]: Fix the configuration issue.`
+    - `[ANCHOR-295]: SEP-6 deposit implementation.`
+- Please make sure to fulfill the pull request templates.
+- When merging the pull request, we suggest to use the squash & commit option.
+
+## Our Git workflow
+
+We use the [Gitflow Workflow](https://www.atlassian.com/git/tutorials/comparing-workflows/gitflow-workflow) for this
+project.
+

docs/01 - Contributing/README.md

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+# How to contribute
+
+<!-- TOC -->
+* [How to contribute](#how-to-contribute)
+  * [Set up the Development Environment](#set-up-the-development-environment)
+  * [Git Guidelines](#git-guidelines)
+  * [Logging Guidelines](#logging-guidelines)
+  * [Database Migration](#database-migration)
+  * [Publishing the SDK library to Maven Central](#publishing-the-sdk-library-to-maven-central)
+  * [Testing with AWS Services](#testing-with-aws-services)
+<!-- TOC -->
+
+👍🎉 First off, thanks for taking the time to contribute! 🎉👍
+
+Check out the [Stellar Contribution Guide](https://github.com/stellar/.github/blob/master/CONTRIBUTING.md) that apply to
+all Stellar projects.
+
+## Set up the Development Environment
+
+Check out
+the [How to set up the development environment](A%20-%20Development%20Environment.md) guide.
+
+## Git Guidelines
+
+Check out the [Git Guidelines](B%20-%20Git%20Guidelines.md) guide.
+
+## Logging Guidelines
+
+When contributing code, think twice about a given log message because not every bit of information is equally important.
+Therefore, the logging levels should be used consistently.
+
+Please follow the [Logging Guidelines](C%20-%20Logging%20Guidelines.md).
+
+## Database Migration
+
+Please refer to [Database Migration](D%20-%20Database%20Migration.md) for information on
+this topic.
+
+## Publishing the SDK library to Maven Central
+
+Please refer to [Publishing the SDK](E%20-%20Publishing%20the%20SDK.md) for information on
+this topic.
+
+## Testing with AWS Services
+
+Please refer to [Testing with AWS Services](F%20-%20Testing%20with%20AWS%20Services.md) for
+information on this topic.