donho/udl-documentation ? reverse-engineered prompt

Build me a clean documentation website for Notepad++ User Defined Languages, using Jekyll and something that works well on GitHub Pages.

I want the site to clearly explain what UDL is, how people can create their own syntax highlighting, and how to use the feature without having to dig through scattered forum posts. Please make it feel like a proper docs site, with a simple homepage, helpful navigation, and separate pages for guides and reference material.

Use the existing content and structure where possible, keep the design polished and easy to read, and make sure it works nicely on mobile too. If anything is unclear, use current Jekyll and GitHub Pages docs online as needed. I’d also like the local setup instructions to be straightforward so someone can run the site and preview changes before publishing.