doc: leave pull requests open for 72 hours

Currently, we have a 48/72 rule for how many hours a pull request should
be left open at a minimum. Unfortunately, whether a pull request should
be left open for 48 or 72 hours is often unclear. The 72 hours is
required if it is a weekend. If I open a pull request on a Friday
morning, does it need to stay open 48 hours or 72 or something in
between? Does it matter if I'm in one time zone or another?

The 48/72 rule predates our fast-tracking process. Given the ability to
fast-track trivial pull requests, there should be little disadvantage to
leaving significant changes open for 72 hours instead of 48 hours, and
arguably considerable advantage in terms of allowing people sufficient
time to review things.

So to simplify, standardize on 72 hours. Weekend or not, 72 hours. Easy.

PR-URL: https://github.com/nodejs/node/pull/22275


Reviewed-By: John-David Dalton <john.david.dalton@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Сково...