Added README.source -- mention for License.

debian/README.source

@@ -0,0 +1,14 @@
+LXQt-config
+-----------
+
+Software Licences
+=================
+
+This software contains GPL v2+, GPL v3+ and LGPL v2+.
+This document
+(http://www.gnu.org/licenses/gpl-faq.html#v3HowToUpgrade)
+tells us GPL v2+ can upgrade GPL v3+. You can upgrade LGPL v3+
+
+see also http://gplv3.fsf.org/dd3-faq
+
+-- Yukiharu YABUKI <yyabuki@debian.org> 2015-08-21 18:42:35+09:00