pro membership conversion disclaimer

rowers/templates/about_us.html

@@ -130,6 +130,10 @@ You will be taken to the secure PayPal payment site.
     "instructions to seller".</li>
 </ul>
 </p>
+<p>After you do the payment, we will manually change your membership to
+  "Pro". Depending on our availability, this may take some time
+  (typically one working day). Don't hesitate to contact us
+  if you have any questions at this stage.</p>
 
 <form action="https://www.paypal.com/cgi-bin/webscr" method="post" target="_top">
 <input type="hidden" name="cmd" value="_s-xclick">