Some projects, such as Zuul itself, need to use python3 to build docs.
This adds a new parameter, sphinx_python, which defines the version
of python to build documentation with. The default is python2 and
projects can choose python3 on a need basis.
Remove the comment about the need for a leading comment, since there
is now a real need for the leading comment anyway.
Replace a few direct references to {{ ansible_user_dir }}/.venv that
should have been using zuul_work_virtualenv.
Update sphinx invocation to source the virtualenv activate first.
Some sphinx modules, such as sphinxcontrib.programoutput, attempt to
execute programs and only invoking sphinx-build with the relative
path causes the paths to not be set up properly.
Co-Authored-By: David Moreau Simard <dmsimard@redhat.com>
Change-Id: Ie5e2c93f88465f4aa746827ff88a585dbaa44fd5
1f8c473765