[3.12] Remove bogus annotations from the descriptor howto guide (GH-112349) (#112352)

Remove bogus annotations from the descriptor howto guide (GH-112349)
(cherry picked from commit d9fc152)

Co-authored-by: Raymond Hettinger <[email protected]>

Author: miss-islington

Doc/howto/descriptor.rst

@@ -521,11 +521,11 @@ everyday Python programs.
 Descriptor protocol
 -------------------
 
-``descr.__get__(self, obj, type=None) -> value``
+``descr.__get__(self, obj, type=None)``
 
-``descr.__set__(self, obj, value) -> None``
+``descr.__set__(self, obj, value)``
 
-``descr.__delete__(self, obj) -> None``
+``descr.__delete__(self, obj)``
 
 That is all there is to it.  Define any of these methods and an object is
 considered a descriptor and can override default behavior upon being looked up