Update broken JSFiddle in Why React blog post (facebook#7783)

Fixes facebook#7782

docs/_posts/2013-06-05-why-react.md

@@ -56,7 +56,7 @@ to the DOM.
 > lightweight description of what the DOM should look like.
 
 We call this process **reconciliation**. Check out
-[this jsFiddle](http://jsfiddle.net/fv6RD/3/) to see an example of
+[this jsFiddle](http://jsfiddle.net/2h6th4ju/) to see an example of
 reconciliation in action.
 
 Because this re-render is so fast (around 1ms for TodoMVC), the developer