docs(README.md): add live demo

README.md

@@ -6,6 +6,10 @@
 
 Showdown is a Javascript Markdown to HTML converter, based on the original works by John Gruber. Showdown can be used client side (in the browser) or server side (with NodeJs).
 
+## Live DEMO
+
+Check a live Demo here http://showdownjs.github.io/demo/
+
 
 ## Installation