added h4 to readme

Closes #3

LGTM given by: @nickux

Squashed commit of the following:

commit 21078c210d1ef25f3ce43d9d2ac813ff859b6744
Author: Nick Johnson <nickj224@gmail.com>
Date:   Tue Dec 10 16:50:42 2013 -0500

    added h4 to readme