Add license headers.

Signed-off-by: XhmikosR <xhmikosr@gmail.com>

scripts/pi-hole/js/groups-domains.js

@@ -1,3 +1,10 @@
+/* Pi-hole: A black hole for Internet advertisements
+ *  (c) 2017 Pi-hole, LLC (https://pi-hole.net)
+ *  Network-wide ad blocking via your own hardware.
+ *
+ *  This file is copyright under the latest version of the EUPL.
+ *  Please see LICENSE file for your rights under this license. */
+
 var table;
 var groups = [];
 const token = $("#token").html();