docs/website/sponsors.html: Zillabit webserver does not support HTTPS

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

docs/website/sponsors.html

@@ -9,7 +9,7 @@
     <div class="panel-body">
       <div class="col-sm-6">
 	<p>The Buildroot community would like to thank
-          <a href="https://www.zillabit.com/">Zillabit</a> for
+          <a href="http://www.zillabit.com/">Zillabit</a> for
 	  donating the <b>buildroot.org</b> domain name and sponsoring
 	  the registration fees 2009 - 2019.</p>
        </div>