MAME's documentation was moved to Sphinx (and thus RST) a number of years ago. I headed up that project, in fact.

There was a significant learning curve getting good output when converting some of the old ASCII charts out of .txt files, but once settled it makes for a much better user experience and it auto-compiles to HTML, PDF, and even EPUB with zero additional effort.

I would definitely not want to go to Markdown from RST for technical documentation that's more complex than a Github readme.