pythongh-65022: Fix description of tuple return value in copyreg (python#103892)

(cherry picked from commit 587f2f0)

Author: hauntsaninja

Doc/library/copyreg.rst

@@ -28,8 +28,8 @@ Such constructors may be factory functions or class instances.
 .. function:: pickle(type, function, constructor_ob=None)
 
    Declares that *function* should be used as a "reduction" function for objects
-   of type *type*.  *function* should return either a string or a tuple
-   containing two or three elements. See the :attr:`~pickle.Pickler.dispatch_table`
+   of type *type*.  *function* must return either a string or a tuple
+   containing between two and six elements. See the :attr:`~pickle.Pickler.dispatch_table`
    for more details on the interface of *function*.
 
    The *constructor_ob* parameter is a legacy feature and is now ignored, but if