Add example of class_methods to dummy app

Author: andyw8

test/dummy/app/models/concerns/verifiable.rb

@@ -13,4 +13,12 @@ def all_verified
       all.select(&:verified?)
     end
   end
+
+  class_methods do
+    def all_unverified
+      all.reject(&:verified?)
+    end
+  end
 end
+
+user = User.new