Do I need to write python code to use it ? No ! Well you may learn Python because it's the best language ever and you could use it for all your projects.
MercurialApp just looks for a file docs/conf.py in your repository. This file is created by Sphinx with the sphinx-quickstart script. If you got one, then MercurialApp will build the doc on each push on the server. Your doc is always up to date !
If you don't use Sphinx, MercurialApp will work as a standard hgweb server.
Want to try it ? Follow the installation steps.