Updates labels-sync.md to:
- Remove [Y/n] prompts that suggested manual confirmation
- Clarify that execution is autonomous
- Document that labels are fetched dynamically (not from reference file)
- Update examples to show actual behavior
- Improve troubleshooting for common issues
- Add user-owned repo handling documentation
Related to #67
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>