Update annual fees section for non-profit organizations

Instead of always waiving fees, mention that they can be waived. 501(c)3
and 501(c)6 organizations are different, so we might want to have
different ways to handle fees.

foundation.gnome.org/about/advisoryboard/index.wml

@@ -105,7 +105,8 @@
       Advisory Board member companies pay an annual fee which helps finance
       the operations of the GNOME foundation. The <a
       href="/reports/">reports</a> that are published by the Foundation show
-      how this money is used to help the GNOME project.</p>
+      how this money is used to help the GNOME project.
+    </p>
 
     <p>There are two levels for commerical companies:</p>
 
@@ -115,8 +116,7 @@
     </ul>
 
     <p>
-      No fee is paid by the invited non-profit organizations that are part
-      of the Advisory Board.
+      Fees may be waived for invited non-profit organizations.
     </p>
 
   </body>