[release] 1.72.0 closed for Beta

From: Michael Caisse (mcaisse-lists_at_[hidden])
Date: 2019-11-08 17:11:38

The master branch is now closed for all changes except by permission for
the Beta release.

Also, remember to add your libraries' changes to the release notes at:

<https://github.com/boostorg/website/blob/master/feed/history/boost_1_72_1.qbk>

Thanks,

-- The Boost Release Team