Refactor admin settings routes

This is much cleaner, and semantically more correct.

app/controllers/admin/settings/registrations_controller.rb

@@ -1,8 +1,8 @@
 class Admin::Settings::RegistrationsController < Admin::SettingsController
-  def index
+  def show
   end
 
-  def create
+  def update
     update_settings
 
     redirect_to admin_settings_registrations_path, flash: {