For format, guidelines and planning see the documentation planning.
The documentation is made available on http://symfony.com/doc/master/cmf/index.html and is regenerated automatically whenever a change is pushed to the master branch on github.
In order to render this documentation locally follow the guidelines on http://readthedocs.org
In short the documentation requires the python tool Sphinx (note not the search engine daemon Sphinx)
to be installed and then generating the documentation should simply require running