Research if pandoc + po4a are good tools for a Tor Browser User Manual in Markdown
Pandoc can turn almost any markup into another markup. The HTML output can be made self-contained using the --self-contained command-line option.
po4a will extract content and merge translations for plain text. It can also do that for Docbook which might be more precise.
The pipeline would be: Markdown → Docbook → Extract / merge translations → HTML.
The --filter option would allow use to easily select sections based on OS or language but is not available on wheezy or the TBB build VM. “Pragma style comments” and sed might do the trick in the short term.
To upload designs, you'll need to enable LFS and have admin enable hashed storage. More information