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: I1c218da39bd623d8ba97332ebb88351d644e29cc
Story: #2002586
Task: #24325

.zuul.yaml

@@ -5,4 +5,4 @@
       - puppet-openstack-integration-jobs-all
       - puppet-openstack-beaker-jobs
       - tripleo-puppet-undercloud
-      - release-notes-jobs
+      - release-notes-jobs-python3