Fix the attribute names in the docstring of GenericAlias (GH-22594)

(cherry picked from commit 77f0a23e7a9fb247101b9b14a060c4ba1c4b87a5)

Co-authored-by: Mikhail Golubev <qsolo825@gmail.com>
diff --git a/Objects/genericaliasobject.c b/Objects/genericaliasobject.c
index 4f95216..3e850b5 100644
--- a/Objects/genericaliasobject.c
+++ b/Objects/genericaliasobject.c
@@ -582,7 +582,7 @@
     .tp_name = "types.GenericAlias",
     .tp_doc = "Represent a PEP 585 generic type\n"
               "\n"
-              "E.g. for t = list[int], t.origin is list and t.args is (int,).",
+              "E.g. for t = list[int], t.__origin__ is list and t.__args__ is (int,).",
     .tp_basicsize = sizeof(gaobject),
     .tp_dealloc = ga_dealloc,
     .tp_repr = ga_repr,