Enable a gitops way of promoting to prod (#582)

<!-- Provide a brief summary of your changes -->

## Motivation and Context
<!-- Why is this change needed? What problem does it solve? -->
The following PR moves away from automatically promoting latest releases
to production in favour of specifying the released version explicitly
via a PR & Review process.

Still sets the image tag to latest for now so we can enable it
separately whenever we decide 👍

## How Has This Been Tested?
<!-- Have you tested this in a real application? Which scenarios were
tested? -->

## Breaking Changes
<!-- Will users need to update their code or configurations? -->

## Types of changes
<!-- What types of changes does your code introduce? Put an `x` in all
the boxes that apply: -->
- [ ] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to change)
- [ ] Documentation update

## Checklist
<!-- Go over all the following points, and put an `x` in all the boxes
that apply. -->
- [ ] I have read the [MCP
Documentation](https://modelcontextprotocol.io)
- [ ] My code follows the repository's style guidelines
- [ ] New and existing tests pass locally
- [ ] I have added appropriate error handling
- [ ] I have added or updated documentation as needed

## Additional context
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-->

Signed-off-by: Radoslav Dimitrov <radoslav@stacklok.com>

docs/guides/contributing/releasing.md

@@ -21,6 +21,8 @@ The release workflow will automatically:
   - `ghcr.io/modelcontextprotocol/registry:vX.Y.Z` - Specific release version
 - Binaries can be downloaded from the GitHub release page
 
+**Note:** Releases do not automatically deploy to production. See the [deployment documentation](../../deploy/README.md) for production deployment instructions.
+
 ## Docker Image Tags
 
 The registry publishes different Docker image tags for different use cases: