Add comment to User model's field list about adding new fields, attr_accessible & only_changed?

When migrating an existing app to Hobo 2.1.2/Rails 4, the new ```attr_accessible``` requirement combined with ```only_changed?``` tripped me up a bit. I lost time trying to figure out why new fields weren't showing up on my User#edit form. It wasn't immediately obvious that I *ALSO* needed include the fields within the list of fields passed to ```only_changed?``` in the ```update_permitted?``` method. This comment could save new users some grief.