better sections for module return docs

docs/docsite/rst/common_return_values.rst

@@ -1,7 +1,5 @@
-.. _common_return_values:
-
-Common Return Values
---------------------
+Return Values
+-------------
 
 .. contents:: Topics
 
@@ -13,6 +11,10 @@ This document covers return values common to all modules.
 .. note:: Some of these keys might be set by Ansible itself once it processes the module's return information.
 
 
+.. _common_return_values:
+
+Common
+^^^^^^
 
 backup_file
 ```````````
@@ -63,8 +65,10 @@ stdout_lines
 When c(stdout) is returned, Ansible always provides a list of strings, each containing one item per line from the original output.
 
 
+.. _internal_return_values:
+
 Internal use
-------------
+^^^^^^^^^^^^
 
 These keys can be added by modules but will be removed from registered variables; they are 'consumed' by Ansible itself.