[3.13] gh-129408: http: Fix typo 'RFF' to RFC' in docstring (GH-129411) (#129414)

gh-129408: http: Fix typo 'RFF' to RFC' in documentation (GH-129411)
(cherry picked from commit 7dd0a7e)

Co-authored-by: Samuel GIFFARD <[email protected]>

Author: miss-islington

Lib/http/__init__.py

@@ -179,7 +179,7 @@ class HTTPMethod:
 
     Methods from the following RFCs are all observed:
 
-        * RFF 9110: HTTP Semantics, obsoletes 7231, which obsoleted 2616
+        * RFC 9110: HTTP Semantics, obsoletes 7231, which obsoleted 2616
         * RFC 5789: PATCH Method for HTTP
     """
     def __new__(cls, value, description):