docs/website: fix Paypal account address

As noticed by Yann E. Morin, the address of the Paypal account is
@buildroot.org, not @lists.buildroot.org.

Reported-by: Yann E. MORIN <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

docs/website/association.html

@@ -87,7 +87,7 @@
 
 	    <li>A Paypal payment to the association Paypal account,
 	    whose address
-	    is <code>buildroot-association@lists.buildroot.org</code>.</li>
+	    is <code>buildroot-association@buildroot.org</code>.</li>
 
 	  </ul>