Update donation link in docs template

Author: aurhat

DOCS_TEMPLATE.html

@@ -54,7 +54,7 @@ <h2>PAGE TITLE HERE</h2>
         <a href="license.html">&copy; Copyright, Rabid Viper Productions</a>
       </div>
       <div id="donatedocs">
-        <a href="https://sourceforge.net/p/actiongame/donate/">
+        <a href="https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=FEUVMQREJMQT2&source=url">
           We would be grateful for any donations considered towards AssaultCube
         </a>
       </div>