bpo-40222: update doc entry with respect to the change in WITH_EXCEPT_START (GH-29975)

Author: iritkatriel

Doc/library/dis.rst

@@ -584,12 +584,14 @@ iterations of the loop.
 
 .. opcode:: WITH_EXCEPT_START
 
-    Calls the function in position 7 on the stack with the top three
+    Calls the function in position 8 on the stack with the top three
     items on the stack as arguments.
     Used to implement the call ``context_manager.__exit__(*exc_info())`` when an exception
     has occurred in a :keyword:`with` statement.
 
     .. versionadded:: 3.9
+    .. versionchanged:: 3.11
+       The ``__exit__`` function is in position 8 of the stack rather than 7.
 
 
 .. opcode:: POP_EXCEPT_AND_RERAISE