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/ftplib.rst b/Doc/library/ftplib.rst
index b6db983..b8f5b4e 100644
--- a/Doc/library/ftplib.rst
+++ b/Doc/library/ftplib.rst
@@ -9,6 +9,10 @@
pair: FTP; protocol
single: FTP; ftplib (standard module)
+**Source code:** :source:`Lib/ftplib.py`
+
+--------------
+
This module defines the class :class:`FTP` and a few related items. The
:class:`FTP` class implements the client side of the FTP protocol. You can use
this to write Python programs that perform a variety of automated FTP jobs, such