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: Ic2c970f3bc7baff38f72e4deaf9fc9c87271be71
Story: #2002586
Task: #24319

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-upgrade-ubuntu-xenial