make __doc__ mutable on heaptypes (closes #12773)
diff --git a/Misc/NEWS b/Misc/NEWS
index 4cf9dda..e30a3cb 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,8 @@
 Core and Builtins
 -----------------
 
+- Issue #12773: Make __doc__ mutable on user-defined classes.
+
 - Issue #12766: Raise an ValueError when creating a class with a class variable
   that conflicts with a name in __slots__.