Update LICENSE

LICENSE

@@ -1,6 +1,18 @@
-While the original author (Originalseed) appears to be unreachable,
-according to https://www.opendesktop.org/p/1080259/ the license of this
-theme (as well as its Emerald, Cinnamon, MDM/GDM and Metacity versions)
-is GPLv2 or later.
+DarkCold - GTK dark theme
+Copyright (C) 2011 originalseed
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
 Metacity support is based on GPLed version of RoyaleVSQ Black by Rob Louw.