gh-102247: Improve documentation of http.HTTPStatus members update (#133190)

Author: loic-simon

Doc/library/http.rst

@@ -139,7 +139,8 @@ equal to the constant name (i.e. ``http.HTTPStatus.OK`` is also available as
 
 .. versionchanged:: 3.13
    Implemented RFC9110 naming for status constants. Old constant names are preserved for
-   backwards compatibility.
+   backwards compatibility: ``413 REQUEST_ENTITY_TOO_LARGE``, ``414 REQUEST_URI_TOO_LONG``,
+   ``416 REQUESTED_RANGE_NOT_SATISFIABLE`` and ``422 UNPROCESSABLE_ENTITY``.
 
 HTTP status category
 --------------------