Add a way to add custom fields to the "meta" section of the sidebar

[qbeauperin]

Following up on David's thread from Discord, it would be nice to have the option to customize the "meta" section in the sidebar.

The current UI suggests that the top of the sidebar is where inputs and user actions happen, while the bottom is more of a "read-only" section. Some use case examples of what would imo fit better down there:

• Live/Preview urls
• Translation progress/status
• Analytics data snippets (page views, average time on page, etc)

Extending the admin.position property might be a way to go about this?

[richadr]

It makes sense to add this.

I'm here because I'm looking for a natural place to add a "live" url.

[qbeauperin]

I've got a very similar use case with preview links, it would make a lot more sense in terms of UX for these to be in that meta section.