Merge "Add doc/requirements.txt to docs tox environment" into stable/queens

tox.ini

@@ -22,6 +22,10 @@ commands =
     doc8 README.rst CONTRIBUTING.rst doc/source
 
 [testenv:docs]
+deps =
+  -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt}
+  -r{toxinidir}/requirements.txt
+  -r{toxinidir}/doc/requirements.txt
 commands = python setup.py build_sphinx
 
 [flake8]