License information for xxHash is not included in README.REDIST.BINS file

### Description

Since PHP 8.1, [xxHash is included in the hash extension](https://github.com/php/php-src/blob/PHP-8.1/ext/hash/xxhash/xxhash.h) and it is under the BSD 2-Clause license.
So it should be noted in README.REDIST.BINS file.

### PHP Version

PHP 8.1

### Operating System

_No response_