#17135: Add note in imp to use importlib for new programs.

Doc/library/imp.rst

-:mod:`imp` --- Access the :keyword:`import` internals
-=====================================================
+:mod:`imp` --- Access the :ref:`import <importsystem>` internals
+================================================================
 
 .. module:: imp
    :synopsis: Access the implementation of the import statement.
@@ -11,6 +11,10 @@ This module provides an interface to the mechanisms used to implement the
 :keyword:`import` statement.  It defines the following constants and functions:
 
 
+.. note::
+   New programs should use :mod:`importlib` rather than this module.
+
+
 .. function:: get_magic()
 
    .. index:: pair: file; byte-code