Update README.md

Author: cheesytim

README.md

@@ -4,7 +4,7 @@
 based on [google-map-react](https://github.com/istarkov/google-map-react) (without recompose :)
 
 ### [Demo](https://tim152.github.io/clustering-google-map-react/)
-<img src="https://github.com/Tim152/clustering-google-map-react/blob/master/public/demo.png" alt="clustering google map react" width="410">
+[<img src="https://github.com/Tim152/clustering-google-map-react/blob/master/public/demo.png" alt="clustering google map react" width="410">](https://tim152.github.io/clustering-google-map-react/)
 
 /src/components/GoogleMap/index.js
 ```javascript