contributing: add new file with a pointer to the wiki
This also includes what I consider to be the minimum set of steps
someone should be able to perform even if they can't run the
testsuite. Hopefully this will help new contributors know to at least
run the two checkers that find most things that (in my experience)
require manual cleanup.
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.