woff2 LICENSE file correction

Good afternoon,

I wanted to give a quick heads up that I have corrected the LICENSE file
that accompanies woff2 to Apache 2 in
https://github.com/google/woff2/commit/0c1ec8895bce7c7b2da66ebc6e9887ef2e0c1a55
to better match file headers and intent.

Let me know if you have any concerns,

Cheers, Rod S.