The CFFI has a nicely done manual. I really liked how it handles the syntax highlighting of Lisp code.
CFFI code contains the colorize-lisp-example.lisp script that post-processes generated HTML documentation to make it look nicer.
In general, I see CFFI as a very nice project that I consider to be quite aspirational in many regards. Its code is high-quality, the documentation is superb and the abstractions are easy to use and flexible.