Update glossary entry for 'loader' to reflect current import system

Author: nikalinov

Doc/glossary.rst

@@ -812,8 +812,11 @@ Glossary
 
    loader
       An object that loads a module. It must define a method named
-      :meth:`load_module`. A loader is typically returned by a
-      :term:`finder`. See also:
+      :meth:`exec_module`, along with :meth:`create_module`.
+      The :meth:`load_module` method, which was used in earlier
+      versions of Python, has been deprecated since version 3.4
+      and should no longer be implemented in new code. A loader is
+      typically returned by a :term:`finder`. See also:
 
       * :ref:`finders-and-loaders`
       * :class:`importlib.abc.Loader`