docs/docs.html: use @buildroot.org for the mailing list

Now that @buildroot.org is working, we should use it everywhere.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

docs/docs.html

@@ -29,7 +29,7 @@ help:</p>
 <ul>
 
   <li>On the <a href="support.html">buildroot mailing list</a>
-  at <code>buildroot at uclibc.org</code></li>
+  at <code>buildroot at buildroot.org</code></li>
 
   <li>On the <a href="irc://freenode.net/#buildroot">Buildroot IRC
   channel</a>, <code>#buildroot</code> on Freenode</li>