Set :wiki menu_item for WikisController#destroy (#35610).

This action is executed inside the project wiki scope after r16916,
thus we can better set the menu_item accordingly.

Patch by Mischa The Evil.

git-svn-id: http://svn.redmine.org/redmine/trunk@21088 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/controllers/wikis_controller.rb

@@ -18,7 +18,7 @@
 # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 
 class WikisController < ApplicationController
-  menu_item :settings
+  menu_item :wiki
   before_action :find_project, :authorize
 
   # Delete a project's wiki