doc: simplify and clarify ReferenceError material in errors.md

"should always be considered" -> "indicate"

PR-URL: https://github.com/nodejs/node/pull/34151


Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Anto Aravinth <anto.aravinth.cse@gmail.com>
Reviewed-By: Christian Clauss <cclauss@me.com>
Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de>
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
Reviewed-By: Andrey Pechkurov <apechkurov@gmail.com>