Clarify how URLs will look like when setting a custom domain

[rodrcastro]

We already do this in the collection-level documentation because of the /v/ situation.

We should also do it for organization and space, as usually customers are confused as to why there's a path at the end of their domain. Moreover, they usually want a "clean" URL with just their custom domain.

This is only achievable if they set the domain on the space-level.

I propose to add this info to the page before specifying where they want to set their domain (this page here) and inside each option like what we have in the collection page, just to make it extra clear.

[sarah-wakefield]

Hey @rodrcastro! For what it's worth, this is detailed in step 2 for all three of the places where a custom domain can be set: https://docs.gitbook.com/publishing/custom-domain/location

Admittedly, people don't always read things in full and in order, so it could well be worth repeating ourselves in future steps of the process.

[rodrcastro]

Yeah, while it's valuable that we already have that info somewhere we can point people to, it might be worth repeating it on each level specifically. Worth clarifying further.