Add contact account to landing page ("Administered by") (#6984)

spec/views/about/show.html.haml_spec.rb

@@ -19,6 +19,7 @@ describe 'about/show.html.haml', without_verify_partial_doubles: true do
                                 hero: nil,
                                 user_count: 0,
                                 status_count: 0,
+                                contact_account: nil,
                                 closed_registrations_message: 'yes')
     assign(:instance_presenter, instance_presenter)
     render