hg-core: simplify `list_tracked_files` operation
Use directly `ListDirstateTrackedFiles` rather than having an operation builder.
Differential Revision: https://phab.mercurial-scm.org/D9013
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.