Update README.md

Author: kevzlou7979

README.md

@@ -61,3 +61,7 @@ Please follow the [contribution document](https://github.com/GwtMaterialDesign/g
  <li><a href="https://github.com/GwtMaterialDesign/gwt-material-template" >Starter</a></li>
  <li><a href="https://github.com/GwtMaterialDesign/gwt-material-patterns" >Patterns</a></li>
 </ul>
+
+## Testing Platform
+<p>Many thanks to BrowserStack for sponsoring our Open Source projects</p>
+<img width="300px" src="https://www.browserstack.com/images/layout/browserstack-logo-600x315.png" href="https://www.browserstack.com/images/layout/browserstack-logo-600x315.png" />