github/training-kit ? reverse-engineered prompt

Build me a simple open source website for Git and GitHub training materials, mostly cheat sheets and quick reference guides. I want it to feel like a polished documentation site, with a clean homepage, easy navigation, and separate pages for each guide. The content should be written in Markdown and rendered as a static site, with a layout that looks good on desktop and mobile.

Please include support for redirects from older pages, downloadable packaged content, and a structure that would make it easy for contributors to add or update cheat sheets later. Keep the design straightforward and professional, similar to GitHub style, and make sure the site is easy to host anywhere, even behind a firewall. If you need to look up current docs or best practices for the build setup, feel free to do that.