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/imaplib.rst b/Doc/library/imaplib.rst
index 1632eb7..2e2c59c 100644
--- a/Doc/library/imaplib.rst
+++ b/Doc/library/imaplib.rst
@@ -342,7 +342,7 @@
 
 .. method:: IMAP4.namespace()
 
-   Returns IMAP namespaces as defined in RFC2342.
+   Returns IMAP namespaces as defined in :rfc:`2342`.
 
 
 .. method:: IMAP4.noop()