Board Thread:Support Requests - Community Management/@comment-5003660-20150327211908/@comment-452-20150426153956

They do not have to give you permission to link to them.

But you shouldn't just go to another wiki and add a link to your wiki on their main page without prior discussion.

(Unless it's a wiki in a shared navigation footer template, in which case their presence in the template means they should be displaying the template on their wiki, and it's perfectly fine to add the footer to their wiki.)