Feature summary:
Currently the homeButton defined in UploadWizard campaigns only allows links to pages on the same wiki (in most cases Commons). It should be possible to link to other Wikis (or even external pages) too.

Use case(s):
This is useful for photo contests where the main page of the contest is on Wikipedia and not on Commons.

Benefits:
Having a link to the contest page would help the new users participating at the Wiki Loves contests to navigate back to the origin page.