Update workflow to only allow releasing from pull requests

.github/workflows/release.yml

@@ -7,6 +7,7 @@ name: Create Release
 
 jobs:
   build:
+    if: github.ref == 'refs/heads/main'
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:

CONTRIBUTING.md

@@ -56,3 +56,37 @@ When [proposing a new feature](https://github.com/gramaziokohler/aixd_ara/issues
 
 * Explain in detail how it would work.
 * Keep the scope as narrow as possible, to make it easier to implement.
+
+# Releasing a new version
+
+Ready to release a new version of the project? Here's how to do it!
+
+We follow [semantic versioning](https://semver.org) principles for our release process.
+To create a new release, follow these steps:
+
+1. Ensure all changes intended for the release are merged into the **main** branch.
+
+2. Create a new branch from **main** to prepare the release (replace `x.y.z` with the version number you plan to release):
+
+   ```bash
+   git checkout main
+   git pull
+   git checkout -b prepare-release-x.y.z
+   ```
+   
+3. Ensure all checks and tests pass successfully. Use the `invoke check` and `invoke test` commands to verify.
+
+4. Decide on the versioning increment type for the release based on the changes since the last version:
+   - `major` for breaking changes to the API
+   - `minor` for adding functionality in a backwards-compatible manner
+   - `patch` for backwards-compatible bug fixes
+
+5. Run the release command with the appropriate release type:
+
+   ```bash
+   invoke release [release_type]
+    ```
+6. Create a merge request to merge the branch into **main**. Check the changes and make sure 
+   everything looks good, before merging.
+
+7. Celebrate! 💃