[mustache demo] Fix link to mustache documentation url

Author: excessivecoding

demo/mustache.html

@@ -61,7 +61,7 @@ <h1>{{title}}</h1>
 </script>
 
     <p>Demonstration of a mode that parses HTML, highlighting
-    the <a href="http://mustache.github.com/">Mustache</a> templating
+    the <a href="http://mustache.github.io/">Mustache</a> templating
     directives inside of it by using the code
     in <a href="../addon/mode/overlay.js"><code>overlay.js</code></a>. View
     source to see the 15 lines of code needed to accomplish this.</p>