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: nodejs#24805
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>

Author: BridgeAR

Diff for: doc/api/util.md

@@ -386,6 +386,9 @@ stream.write('With ES6');
 <!-- YAML
 added: v0.3.0
 changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/24326
+    description: The `depth` default changed back to `2`.
   - version: v11.0.0
     pr-url: https://github.com/nodejs/node/pull/22846
     description: The `depth` default changed to `20`.