Document References and internal links

The latest Scrivener manual includes this Pro Tip:

Pro Tip: If you change the “URL” for internal links (which otherwise just state “[Inter- nal Link]” in the URL field) to a single asterisk, that item will be placed at the very top of the header bar icon menu. If accessed from there, it will load that file in accordance with your navigation settings for internal references. Use this to create a more visible “soft link” between one or more documents, such as frequently used research material, instructions for preparation, and so on.

I do not see how this can be done. The Document Reference section seems to have no title above the first column and the text in that column can’t be separately accessed so I don’t see how you can insert a “!” anywhere. (See screenshot for what I see." I was looking at this tip because I was hoping there was a way to easily “see” if there are document references when you’re operating in a different section of the Inspector.

Thanks for the help.
Scrivner screenshot re Doc Refs.png