doc: recommend queueMicrotask over process.nextTick

We likely cannot ever deprecate process.nextTick, but we can start
steering people towards queueMicrotask for most cases.

Signed-off-by: James M Snell <jasnell@gmail.com>
Fixes: https://github.com/nodejs/node/issues/36870

PR-URL: https://github.com/nodejs/node/pull/37484


Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Robert Nagy <ronagy@icloud.com>