4.0.0 GA timing / expectations

[tianon]

As is Ruby tradition, 4.0.0 is extremely likely to be released/GA'd on Christmas Day (Dec 25th). I'm filing this in advance (especially well before we take off for holiday PTOs) to make it explicitly clear that 4.0.0 will not be published on Christmas Day, and that the soonest we might get to it is going to be Dec 26th (if not sometime in January, given the holiday season). Please be patient. ❤️

(If all goes well, the GA update will get committed here by @docker-library-bot automatically, but the PR to https://github.com/docker-library/official-images will wait until one of us gets to it. 🙇)

See also #488