Motivation
The Popups extension currently only shows popups when the page pointed to (target page) is in namespace 0 --> This makes sense for PagePreviews, but ReferencePreviews should be shown on any page, since source page = target page.

Example

Acceptance Criteria

• Reference previews are visible everywhere where there are footnotes, no matter which namespace

Notes

• The Page previews endpoint is limited to the main namespace. Does the same hold true for the references endpoint?