Fix README incorrect license reference

Was referencing that it was using GPL license, not MIT. 

Which http://fossa.io open source license scanner picked up and triggered on.
このコミットが含まれているのは:
Johan Andersson 2019-05-13 19:46:17 +02:00 committed by GitHub
コミット e83cb168bd
この署名に対応する既知のキーがデータベースに存在しません
GPGキーID: 4AEE18F83AFDEB23
1個のファイルの変更1行の追加1行の削除

ファイルの表示

@ -1,7 +1,7 @@
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