Update README.md

Author: gajus

README.md

@@ -3,7 +3,7 @@
 [![Travis build status](http://img.shields.io/travis/gajus/react-css-modules/master.svg?style=flat)](https://travis-ci.org/gajus/react-css-modules)
 [![NPM version](http://img.shields.io/npm/v/react-css-modules.svg?style=flat)](https://www.npmjs.org/package/react-css-modules)
 
-<img src='./README/react-css-modules' width='150' height='150' />
+<img src='./README/react-css-modules.png' height='150' />
 
 React CSS Modules implement automatic mapping of CSS modules. Every CSS class is assigned a local-scoped identifier with a global unique name. CSS Modules enable a modular and reusable CSS!