Mercurial's documentation is kept in reStructuredText format, which is
a simple plain text format that's easy to read and edit:

  http://docutils.sourceforge.net/rst.html

It's also convertible to a variety of other formats including standard
UNIX man page format and HTML.

To do this, you'll need to install the rst2html and rst2man tools,
which are part of Docutils:

  http://docutils.sourceforge.net/

The rst2man tool is not yet in a stable Docutils release, you have to
install their snapshot, which is what they recommend you run anyway:

  http://docutils.sourceforge.net/docutils-snapshot.tgz

Use the Makefile in this directory to generate the man and HTML pages.