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: Ie8da44c2a1360eece2ea47d131af214e9d4dbec8
Story: #2002586
Task: #24292
diff --git a/doc/source/index.rst b/doc/source/index.rst
index ac57e68..82eda14 100644
--- a/doc/source/index.rst
+++ b/doc/source/index.rst
@@ -245,7 +245,7 @@
 
 
 @decorators.attr
-~~~~~~~~~~
+~~~~~~~~~~~~~~~~
 
 The `attr` decorator is used to set test attributes, this is most commonly used
 to set the test type. Currently, we use one test type "smoke", which should be