fix: remove contributing link to nonexistent CONTRIBUTING.md

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: gkorland

README.md

@@ -215,10 +215,6 @@ Support for additional languages is planned.
 | POST | `/list_commits` | List commits of a repository |
 | POST | `/switch_commit` | Switch to a specific commit |
 
-## Contributing
-
-We welcome contributions! Please see our [Contributing Guide](CONTRIBUTING.md) for details.
-
 ## License
 
 This project is licensed under the MIT License - see the [LICENSE](LICENSE) file for details.