Update LICENSE.md with WordPress Core Licensing

LICENSE.md

@@ -1,3 +1,42 @@
+### WordPress - Web publishing software
+
+    Copyright 2011-2017 by the contributors
+
+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 St, Fifth Floor, Boston, MA  02110-1301  USA
+
+This program incorporates work covered by the following copyright and
+permission notices:
+
+    b2 is (c) 2001, 2002 Michel Valdrighi - m@tidakada.com -
+    http://tidakada.com
+
+    Wherever third party code has been used, credit has been given in the code's
+    comments.
+
+    b2 is released under the GPL
+
+and
+
+    WordPress - Web publishing software
+
+    Copyright 2003-2010 by the contributors
+
+    WordPress is released under the GPL
+
+---
+
 ### GNU GENERAL PUBLIC LICENSE
 
 Version 2, June 1991