string change; moz mkt -> fx mkt

mkt/support/templates/support/mozilla.html

@@ -3,8 +3,8 @@
   {{ csrf() }}
   <p>
     {% trans sumo_url='http://support.mozilla.com' %}
-      Please use this form <strong>only for issues with Mozilla
-      Marketplace</strong>. For other support and questions, please visit
+      Please use this form <strong>only for issues with Firefox
+      Marketplace</strong>. For other support and questions please visit
       <a href="{{ sumo_url }}" target="_blank">support.mozilla.com</a>. We are unable to
       respond to misdirected support requests through this form.
     {% endtrans %}