contributing file update

Author: LucaBonamino

CONTRIBUTING.md

@@ -35,5 +35,20 @@ cargo fmt
 - Add documentation comments (///) for public items
 - Add tests for new functionality when possible
 
+## Versioning
+
+This project follows Semantic Versioning.
+
+General guidelines:
+- CI / workflow changes → no version bump
+- Documentation or README fixes → no version bump
+- Internal refactors with no API change → no version bump
+- Bug fixes affecting users → PATCH bump (maintainer will handle)
+- New backward-compatible features → MINOR bump
+- Breaking changes → MAJOR bump
+
+Releases are handled by the maintainer.
+
+
 ## Question or ideas?
 Feel free to open an issue to discuss changes before starting work.