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: I5f0e7fe263db1a5de89ef5e910df56197cf56f10
Story: #2002586
Task: #24321

.zuul.yaml

@@ -360,11 +360,11 @@
       - openstack-python-jobs
       - openstack-python35-jobs
       - check-requirements
-      - publish-openstack-sphinx-docs
-      - release-notes-jobs
+      - publish-openstack-docs-pti
+      - release-notes-jobs-python3
     check:
       jobs:
-        - build-openstack-sphinx-docs:
+        - openstack-tox-docs:
             vars:
               sphinx_python: python3
         - openstacksdk-ansible-devel-functional-devstack:
@@ -385,7 +385,7 @@
         - nodepool-functional-py35-src
     gate:
       jobs:
-        - build-openstack-sphinx-docs:
+        - openstack-tox-docs:
             vars:
               sphinx_python: python3
         - openstacksdk-functional-devstack