Add release documentation (#814)

## Summary
- describe semantic versioning and release steps
- add release page to documentation nav

## Testing
- `make format`
- `make lint`
- `make mypy`
- `make tests`
- `make build-docs`


------
https://chatgpt.com/codex/tasks/task_i_68409d25afdc83218ad362d10c8a80a1

docs/release.md

@@ -0,0 +1,18 @@
+# Release process
+
+The project follows a slightly modified version of semantic versioning using the form `0.Y.Z`. The leading `0` indicates the SDK is still evolving rapidly. Increment the components as follows:
+
+## Minor (`Y`) versions
+
+We will increase minor versions `Y` for **breaking changes** to any public interfaces that are not marked as beta. For example, going from `0.0.x` to `0.1.x` might include breaking changes.
+
+If you don't want breaking changes, we recommend pinning to `0.0.x` versions in your project.
+
+## Patch (`Z`) versions
+
+We will increment `Z` for non-breaking changes:
+
+- Bug fixes
+- New features
+- Changes to private interfaces
+- Updates to beta features

mkdocs.yml

@@ -72,6 +72,7 @@ plugins:
                     - models/litellm.md
                 - config.md
                 - visualization.md
+                - release.md
                 - Voice agents:
                     - voice/quickstart.md
                     - voice/pipeline.md