switch documentation job to new PTI

This is a mechanically generated patch to switch the documentation
jobs to use the new PTI versions of the jobs 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: I823e47f059e45da39e45d4f8bff6b921a3b93874
Story: #2002586
Task: #24347

.zuul.yaml

@@ -79,7 +79,7 @@
     templates:
       - openstack-python-jobs
       - openstack-python35-jobs
-      - publish-openstack-sphinx-docs
+      - publish-openstack-docs-pti
       - check-requirements
     check:
       jobs:

tox.ini

@@ -26,7 +26,7 @@ passenv = http_proxy HTTP_PROXY https_proxy HTTPS_PROXY no_proxy NO_PROXY
 [testenv:pep8]
 basepython = python3
 commands =
-  doc8 -e .rst doc/source/ CONTRIBUTING.rst HACKING.rst README.rst
+  doc8 -e .rst specs/ doc/source/ CONTRIBUTING.rst HACKING.rst README.rst
   bash tools/flake8wrap.sh {posargs}
   # The following bandit tests are being skipped:
   # B303 - Use of insecure MD2, MD4, or MD5 hash function.
@@ -55,7 +55,6 @@ commands =
 basepython = python3
 deps = -r{toxinidir}/doc/requirements.txt
 commands =
-    doc8 -e .rst specs/ doc/source/ CONTRIBUTING.rst HACKING.rst README.rst
     sphinx-build -W -d doc/build/doctrees -b html doc/source/ doc/build/html
 
 [testenv:debug]