[donations] Mention BTC (#2238)

donations.html

@@ -12,6 +12,8 @@
     <td class="subtitle">Donations</td>
 </tr></table>
 
+<p>You can donate via Bitcoin at <code>17EEDY6MuqLQ3jrTeyYaaUXbc6dFaZEYw7</code> .</p>
+
 <p>You can donate via PayPal here:</p>
 
 <form action="https://www.paypal.com/cgi-bin/webscr" method="post" target="_top">