Doc: Fix link in multiprocessing.starmap pointing to builtin map. (GH-26560)

Author: JulienPalard

Doc/library/multiprocessing.rst

@@ -2242,8 +2242,9 @@ with the :class:`Pool` class.
 
    .. method:: starmap(func, iterable[, chunksize])
 
-      Like :meth:`map` except that the elements of the *iterable* are expected
-      to be iterables that are unpacked as arguments.
+      Like :meth:`~multiprocessing.pool.Pool.map` except that the
+      elements of the *iterable* are expected to be iterables that are
+      unpacked as arguments.
 
       Hence an *iterable* of ``[(1,2), (3, 4)]`` results in ``[func(1,2),
       func(3,4)]``.