Backport source links from 3.x.
Existing links have been updated to use the new reST role. In some
files, I have also made cosmetic changes to the header.
diff --git a/Doc/library/pkgutil.rst b/Doc/library/pkgutil.rst
index 9e634d6..30d4a74 100644
--- a/Doc/library/pkgutil.rst
+++ b/Doc/library/pkgutil.rst
@@ -1,15 +1,18 @@
-
:mod:`pkgutil` --- Package extension utility
============================================
.. module:: pkgutil
:synopsis: Utilities for the import system.
+.. versionadded:: 2.3
+
+**Source code:** :source:`Lib/pkgutil.py`
+
+--------------
+
This module provides utilities for the import system, in particular package
support.
-.. versionadded:: 2.3
-
.. function:: extend_path(path, name)