Add sponsors section

Author: afshinm

index.html

@@ -87,6 +87,10 @@ <h4>Developed with &lt;3</h4>
 
       <div class="footer">
         <p>&copy; <a href='http://usabli.ca/' target="_blank" title="usabli.ca group">usabli.ca</a> 2013 - A weekend project by <a href="http://afshinm.name/" target="_blank">Afshin Mehrabani</a></p>
+
+        <p>If you like Intro.js and would like to support it, you are welcome to make a small donation via <a href="https://pledgie.com/campaigns/23692" target="_blank" rel="nofollow">Pledgie</a>.<br>
+  Sponsors: <a href="http://grossweber.com/b/introjs-1" target="_blank">GROSSWEBER</a> provides software development <a href="http://grossweber.com/b/introjs-2" target="_blank">consulting and training services</a>. We love Intro.js!
+</p>
       </div>
 
     </div>