Fix broken image paths in participant template as well

Author: aiham

sample/Archiving/templates/participant.html

@@ -32,15 +32,15 @@ <h3 class="panel-title">Instructions</h3>
             <tbody>
               <tr>
                 <td style="vertical-align: middle;">Archiving is started</td>
-                <td><img src="img/archiving-on-message.png"></td>
+                <td><img src="static/img/archiving-on-message.png"></td>
               </tr>
               <tr>
                 <td style="vertical-align: middle;">Archiving remains on</td>
-                <td><img src="img/archiving-on-idle.png"></td>
+                <td><img src="static/img/archiving-on-idle.png"></td>
               </tr>
               <tr>
                 <td style="vertical-align: middle;">Archiving is stopped</td>
-                <td><img src="img/archiving-off.png"></td>
+                <td><img src="static/img/archiving-off.png"></td>
               </tr>
             </tbody>
           </table>