Add new image

Author: afshinm

README.md

@@ -25,7 +25,7 @@ Optionally, pass one parameter to `introJs` function to limit the presentation s
 
 **For example** `introJs(".introduction-farm").start();` runs the introduction only for elements with `class='introduction-farm'`.
 
-<p align="center"><img src="http://usablica.github.com/intro.js/img/introjs-demo.jpg"></p>  
+<p align="center"><img src="http://usablica.github.com/intro.js/img/introjs-demo.png"></p>  
 
 
 ## Using with: