Mention the info message on many computers

wiki/src/install/inc/steps/pc_boot_menu.inline.html

@@ -63,6 +63,11 @@ following screenshot is an example of such boot menu:</p>
     <tr><td>Toshiba</td><td>F12</td></tr>
     <tr><td>others&hellip;</td><td>F12, Esc</td></tr>
   </table>
+
+  <div class="tip">
+  <p>On many computers, a message is displayed very briefly when switching on
+  that also explains how to get to the boot menu or edit the BIOS settings.</p>
+  </div>
 </li>
 
 <li>