include substs in new todo file

Signed-off-by: martin f. krafft <madduck@madduck.net>
diff --git a/doc/source/todo.rst b/doc/source/todo.rst
index 9f27242..8da2ed3 100644
--- a/doc/source/todo.rst
+++ b/doc/source/todo.rst
@@ -57,3 +57,5 @@
 
 Ideally, |reclass| could unify the interface so that even templates can be
 shared between the various CMS.
+
+.. include:: substs.inc