This guide assumes that you already have a Sphinx documentation project configured and building. If that is not the case, see the Sphinx documentation first and then come back.
The first thing you will need to do is install sphinx-git:
pip install sphinx-git
You may also want to include it in your setup.py or requirements.txt to ensure that sphinx-git is installed wherever you generate your documentation; each project will probably have a different way of doing this.
Once you have installed sphinx-git, you need to configure Sphinx to look for it. Find the Sphinx conf.py which is used to generate your documentation. Somewhere in that file (generally towards the top), you will find the extensions setting. Add sphinx_git to this list (note the underscore):
extensions = ['sphinx_git']
All the hard parts are done, now you can add a git changelog to your project! Find a documentation file where you want it and add:
Recent Changes
--------------
.. git_changelog::
Build your documentation and, voila!, you have a git changelog right there in your docs!
There are a number of ways you can configure sphinx-git to output precisely what you want, which are outlined in the next section of the documentation.