docs: Refresh main README.md display

Force GitHub to refresh main README.md display.

GitHub may have cached or displayed wrong README file.
This empty commit with README.md staged will trigger GitHub to
re-render the main README.md on repository page.

If GitHub still shows .github/README.md instead:
1. Wait a few minutes for GitHub to refresh
2. Clear browser cache
3. Hard refresh page (Ctrl+Shift+R)
4. Check if issue persists

Main README.md is at:
- File: README.md (15535 characters, 497 lines)
- Format: Correct Markdown
- First line: # RainingKeys (Python)
- Content: Complete project documentation

Author: Ian-bug