LICENSE.md should say contributions are made under GPU for the Web 3-Clause BSD License

[dneto0]

That should be carried over from the gpuweb/gpuweb repo

Also, my preference is to copy the license text into this repo as well, so this repo is more self-contained.

[mehmetoguzderin]

@dneto0 isn't it better to keep it linked to one in admin to benefit from any changes there? I think it is an acceptable practice for license files to link.

BTW I update the LICENSE.md (since we're bootstrapping the repo), is it better now?