Simplify readme (the snippet doesn't need explanation)

Author: kirs

README.md

@@ -327,8 +327,6 @@ And `app/views/conferences/_presentation_fields.html.erb` would be:
 
 ActiveForm also can accept `ActiveModel::Model` instances as a model.
 
-Let's define the Feeback class class with `ActiveModel::Model` that will be used for customer's feedback:
-
 ```ruby
 class Feedback
   include ActiveModel::Model