[nyanpasu64]

The styling looks familiar from Meson's website at https://mesonbuild.com/, and checking Inspect Element on Meson's site reveals hotdoc references in the HTML source. Though I still don't know if it's better than other docs/website frameworks.

[HaoZeke]

It is the framework used by meson which was how I came across it. It's different, for short API documentation the yaml structure probably works better.