tests: stabilize test-git-interop.t for some versions of git
Not sure why this differs on my system, but it's likely due to running 2.17.1 on
Ubuntu 18.04.
Differential Revision: https://phab.mercurial-scm.org/D10520
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. You'll need to install Docutils:
http://docutils.sourceforge.net/
Use the Makefile in this directory to generate the man and HTML pages.