Simplify ryu license header

Author: byroot

ext/json/ext/vendor/ryu.h

@@ -3,13 +3,8 @@
 // The contents of this file may be used under the terms of the Apache License,
 // Version 2.0.
 //
-//    (See accompanying file LICENSE-Apache2 or copy at
-//     http://www.apache.org/licenses/LICENSE-2.0)
-//
 // Alternatively, the contents of this file may be used under the terms of
 // the Boost Software License, Version 1.0.
-//    (See accompanying file LICENSE-Boost or copy at
-//     https://www.boost.org/LICENSE_1_0.txt)
 //
 // Unless required by applicable law or agreed to in writing, this software
 // is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY