docs: improve documentation

- improves formatting on variables section
- adds Gitlab information
- adds Gitlab CI example

README.md

@@ -2,41 +2,92 @@
 
 [![Build Status](https://cloud.drone.io/api/badges/commitsar-app/release-notary/status.svg)](https://cloud.drone.io/commitsar-app/release-notary)
 
-Release Notary builds release notes using [Conventional Commit](https://www.conventionalcommits.org/) standard and then publishes it to Github. Release notes are appended to any text you already have in your release and therefore will not affect important announcements etc. Currently only Github is supported, but Gitlab is on the way as well.
+Release Notary builds release notes using [Conventional Commit](https://www.conventionalcommits.org/) standard and then publishes it to Github. Release notes are appended to any text you already have in your release and therefore will not affect important announcements etc.
 
-Heavily inspired by https://github.com/graphql/graphql-js/releases but usable as a standalone app.
+Currently supported providers are: `[Github, Gitlab]`.
+
+Heavily inspired by https://github.com/graphql/graphql-js/releases, but usable as a standalone app.
 
 Expected output is [HERE](./expected-output.md)
 
-:warning: **Currently experimental.** :warning:
+:warning: **Currently experimental. Please report any issues** :warning:
 
 ### Table of contents
 
-1. [Usage](#usage)
+1. [Setup](#setup)
+   - [Github](#github)
+   - [Gitlab](#gitlab)
+2. [Usage](#usage)
 
-## Usage
+## Setup
+
+### Github
+
+**Variables:**
+
+| Name              | Example value                                                                                                                          | Required |
+| ----------------- | -------------------------------------------------------------------------------------------------------------------------------------- | -------- |
+| GITHUB_TOKEN      | token (provided in Github Action or [HERE](https://help.github.com/en/articles/creating-a-personal-access-token-for-the-command-line)) | true     |
+| GITHUB_REPOSITORY | commitsar-app/commitsar                                                                                                                | true     |
+
+In Github actions GITHUB_REPOSITORY is provided in the correct format. Does not need to be explicitly added.
 
-#### Required variables
+In Github actions GITHUB_TOKEN is provided with the correct access rights, elsewhere it needs to be generated and added to the pipeline. Please see the [usage](#usage) section.
 
-- GITHUB_TOKEN
-- GITHUB_REPOSITORY (in the format of `owner/repository` e.g. `commitsar-app/release-notary`)
+### Gitlab
+
+**Variables:**
+
+In Gitlab CI all the values are provided except for `GITLAB_TOKEN`. Documentation provided [here](https://docs.gitlab.com/ee/ci/variables/predefined_variables.html).
+
+| Name          | Example value             | Required |
+| ------------- | ------------------------- | -------- |
+| GITLAB_TOKEN  | token                     | true     |
+| CI_API_V4_URL | https://gitlab.com/api/v4 | true     |
+| CI_COMMIT_TAG | v0.0.4                    | true     |
+| CI_PROJECT_ID | 1234                      | true     |
+
+## Usage
 
 #### Using Github actions
 
-Checkout git in order to get commits and master branch
+Should be run only on tags, example is [HERE](https://github.com/commitsar-app/commitsar/blob/master/.github/workflows/release.yml):
 
+```yml
+on:
+  push:
+    tags:
+      - "v*"
 ```
+
+Checkout git in order to get commits and master branch
+
+```yml
 - name: Check out code into the Go module directory
   uses: actions/checkout@v1
 ```
 
 Run the Release Notary action. Github token needs to be explicitly added so that Release Notary can use it. See https://help.github.com/en/articles/virtual-environments-for-github-actions
 
-```
+```yml
 - name: Release Notary Action
   uses: commitsar-app/[email protected] (substitute for current version)
   env:
-      GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+    GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+```
+
+#### Gitlab CI
+
+```yml
+release:
+  stage: release
+  variables:
+    GITLAB_TOKEN: $RELEASE_TOKEN
+  image: commitsar/release-notary
+  script:
+    - release-notary publish
+  only:
+    - tags
 ```
 
 #### Using binary
@@ -46,9 +97,8 @@ Download and run: **(Substitute v0.0.2 for current version)**
 ```yml
 - curl -L -O https://github.com/commitsar-app/release-notary/releases/download/v0.0.2/release-notary_v0.0.2_Linux_x86_64.tar.gz
 - tar -xzf release-notary_v0.0.2_Linux_x86_64.tar.gz
+# Set up any required variables
 - export GITHUB_TOKEN=yourtoken
 - export GITHUB_REPOSITORY=owner/repo
 - ./release-notary publish
 ```
-
-Gitlab release documentation: https://gitlab.com/help/api/releases/index.md