sleep, sleep-until, & sleep-timer are under Date but belong elsewhere #4628
Description
sleep & sleep-timer both take a Real representing seconds of time. sleep-until takes an Instant, but also automatically coerces a DateTime argument to Instant.
None of this has anything remotely to do with the Date class.
It would make more sense to document these three subs under DateTime if we want to keep them in a class, or else in the independent routines section, especially for people browsing or systematically reading the docs and not just searching for one item.