doc: mention util depth default change

This was missed when reverting a former commit. To make sure the
history is kept in place, this just adds a new entry to state the
revert.

PR-URL: https://github.com/nodejs/node/pull/24805


Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>