add built with marked to README

Author: Jonathon Kelly

README.md

@@ -7,7 +7,7 @@
 
 [![NPM](https://nodei.co/npm/react-markdown-renderer.png?downloads=true&downloadRank=true)](https://nodei.co/npm/react-markdown-renderer/)
 
-Simple React component that renders Markdown
+Simple React component that renders Markdown, built with [marked](https://github.com/chjj/marked). 
 
 ## Installing