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

Fix doc8 failures. Move doc8 to pep8 environment following PTI.

Change-Id: I5e236be20940ae6840eff804804b99f42cd6fcb2
Story: #2002586
Task: #24319

doc/source/app-ovn.rst

@@ -36,12 +36,13 @@ Prerequisites
 
 * Open vSwitch >= 2.9.0
 
-* Networking-ovn at time of writing requires neutron-lib>=1.17.0. The overrides
+* Networking-ovn at time of writing requires neutron-lib>=1.17.0. The
-described here will ensure that version is installed.
+  overrides described here will ensure that version is installed.
 
-* A successful deployment of OVN requires a dedicated network interface be
+* A successful deployment of OVN requires a dedicated network
-attached to the OVS provider bridge. This is not handled automatially and
+  interface be attached to the OVS provider bridge. This is not
-may require changes to the network interface configuration file.
+  handled automatially and may require changes to the network
+  interface configuration file.
 
 OpenStack-Ansible user variables
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tox.ini

@@ -38,7 +38,6 @@ basepython = python3
 deps = -r{toxinidir}/doc/requirements.txt
 commands=
     bash -c "rm -rf doc/build"
-    doc8 doc
     sphinx-build -b html doc/source doc/build/html
 
 
@@ -64,6 +63,7 @@ commands =
 [testenv:pep8]
 commands =
     bash -c "{toxinidir}/tests/common/test-pep8.sh"
+    doc8 doc
 
 
 [flake8]

zuul.d/project.yaml

@@ -16,8 +16,8 @@
     templates:
       - openstack-ansible-role-jobs
       - check-requirements
-      - publish-openstack-sphinx-docs
+      - publish-openstack-docs-pti
-      - release-notes-jobs
+      - release-notes-jobs-python3
     check:
       jobs:
         - openstack-ansible-ovs-ubuntu-xenial