bpo-33641: Convert RFC references into links. (GH-7103)


85% of them are already links.
(cherry picked from commit 0a36ac1a09587735237c5978ebd046313922869c)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
diff --git a/Doc/tutorial/stdlib.rst b/Doc/tutorial/stdlib.rst
index 6ac29fc..f5ec8ac 100644
--- a/Doc/tutorial/stdlib.rst
+++ b/Doc/tutorial/stdlib.rst
@@ -317,7 +317,7 @@
   names, no direct knowledge or handling of XML is needed.
 
 * The :mod:`email` package is a library for managing email messages, including
-  MIME and other RFC 2822-based message documents. Unlike :mod:`smtplib` and
+  MIME and other :rfc:`2822`-based message documents. Unlike :mod:`smtplib` and
   :mod:`poplib` which actually send and receive messages, the email package has
   a complete toolset for building or decoding complex message structures
   (including attachments) and for implementing internet encoding and header