Help text is only accurate for coupled sites

Problem/Motivation

There is default text guidance that says:

Start typing the title of a piece of content to select it. You can also enter an internal path such as /node/add or an external URL such as http://example.com. Enter <front> to link to the front page. Enter <nolink> to display link text only. Enter <button> to display keyboard-accessible link text only.

However, this is only accurate for coupled sites. For decoupled sites, the second half of this guidance may not be accurate and may create broken links or confusing editorial experiences.

Proposed resolution

A simple resolution might be to allow substitute text guidance be available for decoupled/headless sites that can be selected to be used when needed that is only:

Start typing the title of a piece of content to select it. You can also enter an internal path such as /node/add or an external URL such as http://example.com.

An additional resolution might be to allow the option to set custom text guidance in the field UI