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/rlcompleter.rst b/Doc/library/rlcompleter.rst
index 85a9d79..318b3ea 100644
--- a/Doc/library/rlcompleter.rst
+++ b/Doc/library/rlcompleter.rst
@@ -1,4 +1,3 @@
-
 :mod:`rlcompleter` --- Completion function for GNU readline
 ===========================================================
 
@@ -6,6 +5,9 @@
    :synopsis: Python identifier completion, suitable for the GNU readline library.
 .. sectionauthor:: Moshe Zadka <moshez@zadka.site.co.il>
 
+**Source code:** :source:`Lib/rlcompleter.py`
+
+--------------
 
 The :mod:`rlcompleter` module defines a completion function suitable for the
 :mod:`readline` module by completing valid Python identifiers and keywords.