Redirect cheat sheet to cheatsheet.grc.engineering

Old URL now redirects to the new subdomain-based deployment.

Generated with [Claude Code](https://claude.ai/code)
via [Happy](https://happy.engineering)

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

Author: 3 people