Add copyright in README.asciidoc

README.asciidoc

@@ -51,3 +51,22 @@ Wait some months...
 WeeChat still not crashed and does not use 200 TB of RAM ? +
 Yeah, it's stable! \o/
+
+== Copyright
+
+Copyright (C) 2011-2014 Sébastien Helleu <flashcode@flashtux.org>
+
+This file is part of weercd, the extensible chat client.
+
+weercd 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 3 of the License, or
+(at your option) any later version.
+
+weercd 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 weercd.  If not, see <http://www.gnu.org/licenses/>.