Content that won't have a URL

In an older version (9 or 10), I had followed a tutorial for having some shared content in a page outside the normal navigation.

I’ve created a similar thing in 15: A “content settings” document type that holds shared content that can be displayed in various places.

My “content settings” is a second root document that shouldn’t have public urls

When I save and publish I get warnings because there are no domains configured for it.

Is there a better way to approach this?