admin/accounts: for maintainers, show the button to remove the role

Author: Trim

app/views/admin/accounts/index.html.haml

@@ -72,6 +72,8 @@
       %td
         - if account.editor?
           = button_to "Simple visiteur", admin_account_editor_path(account.id), method: :delete, class: "change_role"
+        - if account.maintainer?
+          = button_to "Simple visiteur", admin_account_maintainer_path(account.id), method: :delete, class: "change_role"
         - elsif account.moderator?
           = button_to "Simple visiteur", admin_account_moderator_path(account.id), method: :delete, class: "change_role"
         - elsif account.admin?