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/library/email.examples.rst b/Doc/library/email.examples.rst
index 84e9aee..fc96462 100644
--- a/Doc/library/email.examples.rst
+++ b/Doc/library/email.examples.rst
@@ -12,7 +12,7 @@
 .. literalinclude:: ../includes/email-simple.py
 
 
-Parsing RFC822 headers can easily be done by the using the classes
+Parsing :rfc:`822` headers can easily be done by the using the classes
 from the :mod:`~email.parser` module:
 
 .. literalinclude:: ../includes/email-headers.py