The site for the Airflow documentation that used to be located at pythonhosted.org is now located at http://airflow.incubator.apache.org/
It's a static site that is sourced from `https://git-wip-us.apache.org/repos/asf/incubator-airflow-site.git` on the `asf-site` branch.
This should point to latest stable, while readthedocs.org keeps track of versioned documentation.
To build the docs, run `python setup.py build_sphinx` from the main airflow project, this builds a static site under `docs/_build/html/`. You can then copy the content of this folder to root of the repo/branch mentioned above.
Alternatively, you can `cd docs; ./build.sh`
(Incomplete) List of Python packages required to build the docs: