[PR #9455/d887930e backport][stable-9] normalize docs in callback plugins (#9466)

normalize docs in callback plugins (#9455)

* normalize docs in callback plugins

Normalize doc blocks for plugins

* Apply suggestions from code review

Co-authored-by: Felix Fontein <felix@fontein.de>

---------

Co-authored-by: Felix Fontein <felix@fontein.de>
(cherry picked from commit d887930e49)

Co-authored-by: Alexei Znamensky <103110+russoz@users.noreply.github.com>

plugins/callback/context_demo.py

@@ -7,17 +7,17 @@
 from __future__ import (absolute_import, division, print_function)
 __metaclass__ = type
 
-DOCUMENTATION = '''
-    author: Unknown (!UNKNOWN)
-    name: context_demo
-    type: aggregate
-    short_description: demo callback that adds play/task context
-    description:
-      - Displays some play and task context along with normal output.
-      - This is mostly for demo purposes.
-    requirements:
-      - whitelist in configuration
-'''
+DOCUMENTATION = r"""
+author: Unknown (!UNKNOWN)
+name: context_demo
+type: aggregate
+short_description: demo callback that adds play/task context
+description:
+  - Displays some play and task context along with normal output.
+  - This is mostly for demo purposes.
+requirements:
+  - whitelist in configuration
+"""
 
 from ansible.plugins.callback import CallbackBase