update artiq users/contributors

artiq/index.html

@@ -100,7 +100,8 @@
         <td><a href="https://www2.physics.ox.ac.uk/"><img src="logo_oxford.png"></a></td>
         <tr><td><a href="http://jqi.umd.edu/"><img src="logo_jqi.png"></a></td>
         <td><img src="logo_arl.png"></td></tr>
-        <tr><td><a href="http://www.duke.edu"><img src="logo_duke.png"></a></td><td></td></tr>
+        <tr><td><a href="http://www.duke.edu"><img src="logo_duke.png"></a></td>
+        <td><a href="https://www.qsim.uni-freiburg.de/"><img src="logo_freiburg.png"></a></td></tr>
         </table></center>
         </p>
     </div>