Update GitHub release notes template with best practices

Standardize release note documentation with clear, consistent formatting guidelines. This helps maintainers create more informative and readable release communications.

- Add recommended sections: Added, Changed, Fixed
- Specify preferred section order and headers
- Include guidance on summary and section handling
- Use markdown h2 headers for sections

Author: bartTC

CLAUDE.md

@@ -50,6 +50,26 @@ just dmg                   # Create DMG installer
 gh release create v0.0.X   # Create GitHub release with assets
 ```
 
+### GitHub Release Notes Format
+
+```
+One paragraph summary of the release.
+
+## Added
+- New features
+
+## Changed
+- Changes to existing functionality
+
+## Fixed
+- Bug fixes
+```
+
+- Summary paragraph first (no header)
+- Sections use `##` (h2) headers
+- Section order: Added → Changed → Fixed
+- Omit empty sections
+
 ### App Store
 
 ```bash