This is the official documentation for coala, and it is online at https://docs.coala.io. The coala repository can be found here.
You should run this command before trying to build the documentation:
pip3 install -r docs-requirements.txt
You can test the documentation locally through simply running
make html
in the root directory. This generates _buildhtmlindex.html that you can view on your browser.
If you want to add new pages, you need to alter the index.rst file in the root directory. Please read http://www.sphinx-doc.org/en/stable/markup/toctree.html#toctree-directive for an explanation of the syntax.