docs: add CONTRIBUTING.md to guide contributors (#88)

Signed-off-by: Pranam <[email protected]>

CONTRIBUTING.md

@@ -0,0 +1,90 @@
+Thank you for considering contributing to OpenFeature Rust SDK!
+We appreciate your help and look forward to collaborating with you.
+
+Here are the key steps for contributing to the OpenFeature Rust SDK:
+
+## How to Contribute
+
+1. **Fork the Repository**: Create a personal fork of the [repository](https://github.com/open-feature/rust-sdk.git) on GitHub.
+2. **Clone Your Fork**:
+   ```sh
+   mkdir open-feature
+   cd open-feature
+   git clone https://github.com/YOUR_GITHUB_USERNAME/rust-sdk.git
+   cd rust-sdk
+   ```
+3. **Create a Branch**: Create a new branch with a name that follows the recommended convention:
+    ```sh
+    git checkout -b <prefix>/<gh-issue-number>
+    ```
+    - If there is a corresponding GitHub issue number, include it in the branch name.
+    - Otherwise, name the branch meaningfully, using hyphens to replace spaces.
+    - Use the following prefixes based on the type of change:
+      - 🐛 Bug Fixes: `fix/<description>` or `fix/<issue-number>`
+      - ✨ New Features: `feat/<description>` or `feat/<issue-number>`
+      - 🧹 Chore: `chore/<description>` or `chore/<issue-number>`
+      - 📚 Documentation: `docs/<description>` or `docs/<issue-number>`
+      - 🚀 Performance: `perf/<description>` or `perf/<issue-number>`
+      - 🛠️ Build: `build/<description>` or `build/<issue-number>`
+      - 📦 Dependencies: `deps/<description>` or `deps/<issue-number>`
+      - 🚦 CI: `ci/<description>` or `ci/<issue-number>`
+      - 🔄 Refactoring: `refactor/<description>` or `refactor/<issue-number>`
+      - 🔙 Reverts: `revert/<description>` or `revert/<issue-number>`
+      - 🎨 Styling: `style/<description>` or `style/<issue-number>`
+      - 🧪 Tests: `test/<description>` or `test/<issue-number>`
+
+4. **Make Changes**: Implement your changes or additions to the codebase.
+5. **Commit Changes**: Stage your changes and commit them with a descriptive message.
+6. **Push to Your Fork**: Push your branch to your forked repository.
+7. **Create a Pull Request**: Open a pull request from your forked repository to the main OpenFeature Rust SDK repository.
+8. **Address Feedback**: If there are any comments or requested changes, address them in your branch and push the updates.
+9. **Merge**: Once your pull request is approved, it will be merged into the main repository.
+
+## Development Setup
+
+To set up your development environment, ensure you have the following installed:
+
+- [Rust & Cargo](https://www.rust-lang.org/tools/install)
+- [VS Code](https://code.visualstudio.com)
+- [Rust Analyzer VS Code Extension](https://marketplace.visualstudio.com/items?itemName=rust-lang.rust-analyzer)
+
+After installing Rust, you can verify your installation with following command:
+
+```sh
+rustc --version
+```
+
+After installing Cargo, you can verify your installation with following command:
+
+```sh
+cargo --version
+```
+
+## Build, Test, Document and Run the Project
+
+To build the project, execute the following command:
+```sh
+cargo build
+```
+
+To test the project, execute the following command:
+```sh
+cargo test
+```
+
+To build documentation for the project, execute the following command:
+```text
+cargo doc
+```
+
+To run the project, execute the following command:
+```sh
+cargo run
+```
+
+## Closing Note
+
+Thank you 🙏 for your interest and support!
+Your contributions help us improve and grow 🌱 the OpenFeature Rust SDK.
+We truly appreciate your time and effort in making our project better.
+If you have any questions or need assistance, please don’t hesitate to reach out on Slack in the [#openfeature-rust](https://cloud-native.slack.com/archives/C05RG7F93NV) channel!