openstack-tox-docs is part of docs-on-readthedocs template,
so remove it from check/gate - it's really redundant.
Change-Id: Iae1222b83a70060b5e2a73b1b937815124629e6b
This is a mechanically generated patch to add a unit test job running
under Python 3.6 as part of the python3-first goal.
See the python3-first goal document for details:
https://governance.openstack.org/tc/goals/stein/python3-first.html
Change-Id: I5f0fcb8bf50216ee8ffa9701972d1a5001be1060