This allows you to include a git changelog of your Sphinx documentation
within the documentation.

To use it, add 'sphinx_git' to 'extensions' in your Sphinx conf.py, and add:

.. git_changelog::

where you want the list of commits to appear.  This will display 10 commits by
default; if you want a different number then pass in the revisions option:

.. git_changelog::
  :revisions: 5
