Missing file declaring terms of the license

[Conan-Kudo]

This library is declared to be licensed under Boost Software License, Version 1.0.

Please provide a copy in this repository as a COPYING or LICENSE file for downstream users/redistributors to know the terms of the license. This is especially important for me, as I'm packaging mustache-d for Fedora.

[Conan-Kudo]

Incidentally, terms of the Boost license indicate you need to distribute a copy of the license.

Per the license itself:

The copyright notices in the Software and this entire statement, including
the above license grant, this restriction and the following disclaimer,
must be included in all copies of the Software