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/hashlib.rst b/Doc/library/hashlib.rst
index eda18ad..0ed0482 100644
--- a/Doc/library/hashlib.rst
+++ b/Doc/library/hashlib.rst
@@ -283,7 +283,7 @@
 .. index::
    single: blake2b, blake2s
 
-BLAKE2_ is a cryptographic hash function defined in RFC-7693_ that comes in two
+BLAKE2_ is a cryptographic hash function defined in :rfc:`7693` that comes in two
 flavors:
 
 * **BLAKE2b**, optimized for 64-bit platforms and produces digests of any size
@@ -707,7 +707,6 @@
 
 * *Alexandr Sokolovskiy*
 
-.. _RFC-7693: https://tools.ietf.org/html/rfc7693
 .. _BLAKE2: https://blake2.net
 .. _HMAC: https://en.wikipedia.org/wiki/Hash-based_message_authentication_code
 .. _BLAKE: https://131002.net/blake/