enable indexer using `compose.indexer.yml` on self-host:
```bash
docker compose -f compose.yml -f compose.indexer.yml up
```
<!-- This is an auto-generated comment: release notes by coderabbit.ai -->
## Summary by CodeRabbit
- **Chores**
- Updated the build process in the development container to include building the reader package.
- Added and configured a Manticore Search indexer service in the development container.
- Removed the indexer service and related environment variables from the self-hosted Docker Compose setup and environment example file.
- **Documentation**
- Improved documentation formatting for better readability.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
