[boost] [release] Release notes for 1.65.0 beta

Hi, If you haven't done so yet, please write your release notes for 1.65.0 beta. You can create a pull request at: https://github.com/boostorg/website/blob/master/feed/history/boost_1_65_0.qb... Or if you'd rather you can send them to me, and I'll add them for you. thanks, Daniel