Update obj2sdf.cpp

Extras/obj2sdf/obj2sdf.cpp

@@ -4,6 +4,20 @@
 /// this will make it easier to load complex obj files into pybullet
 /// see for example export in data/kitchens/fathirmutfak.sdf
 
+///Bullet Continuous Collision Detection and Physics Library
+///Erwin Coumans (C) 2018
+///http://bulletphysics.org
+///
+///This software is provided 'as-is', without any express or implied warranty.
+///In no event will the authors be held liable for any damages arising from the use of this software.
+///Permission is granted to anyone to use this software for any purpose,
+///including commercial applications, and to alter it and redistribute it freely,
+///subject to the following restrictions:
+///
+///1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
+///2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
+///3. This notice may not be removed or altered from any source distribution.
+
 #include <string.h>
 #include <stdio.h>
 #include <assert.h>