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/nntplib.rst b/Doc/library/nntplib.rst
index 7a461b4..acbb7a5 100644
--- a/Doc/library/nntplib.rst
+++ b/Doc/library/nntplib.rst
@@ -10,6 +10,10 @@
pair: NNTP; protocol
single: Network News Transfer Protocol
+**Source code:** :source:`Lib/nntplib.py`
+
+--------------
+
This module defines the class :class:`NNTP` which implements the client side of
the NNTP protocol. It can be used to implement a news reader or poster, or
automated news processors. For more information on NNTP (Network News Transfer