Merge pull request #5542 from tk0miya/5438_update_CHANGES

Update CHANGES (refs: #5438)

CHANGES

@@ -151,7 +151,7 @@ Deprecated
 * :confval:`autodoc_default_flags` is deprecated
 * quickstart: ``--epub`` option becomes default, so it is deprecated
 * Drop function based directive support.  For now, Sphinx only supports class
-  based directives.
+  based directives (see :class:`~Directive`)
 * ``sphinx.util.docutils.directive_helper()`` is deprecated
 * ``sphinx.cmdline`` is deprecated
 * ``sphinx.make_mode`` is deprecated