[Wiki] Make it obvious that e-mail verification is required for editing

[Aleksej]

Editing or creating pages in the wiki requires that the e-mail
address is *verified* (that you are in the emailconfirmed group).

The only place I found where the wiki says so is the "View source"
pages which replace the "Edit" pages for pages one cannot edit.
Those "View source" pages are available by clicking the "View
source" link (which already says you cannot edit, so would you
click it?), and not (at least easily) available for user pages.