Update README.md

Author: nikolas

README.md

@@ -1,9 +1,12 @@
 # markdown-toolbar [![Build Status](https://travis-ci.org/nikolas/markdown-toolbar.svg?branch=master)](https://travis-ci.org/nikolas/markdown-toolbar) [![Greenkeeper badge](https://badges.greenkeeper.io/nikolas/markdown-toolbar.svg)](https://greenkeeper.io/)
 
-A clone of GitHub's markdown toolbar
+A clone of GitHub's markdown toolbar.
 
 ![markdown-toolbar screenshot](http://www.columbia.edu/~njn2118/journal/img/markdown-toolbar.png)
 
+* Demo: https://nikolas.github.io/markdown-toolbar/
+* Background info: http://www.columbia.edu/~njn2118/journal/2016/2/12.html
+
 ## Usage
 
 ```js