Documentation still refers to `klass` config option

[finalburn]

If you use the klass option in config, e.g.:

class Card < ApplicationRecord
  include RemoteRecord
  remote_record do |c|
    c.klass RemoteRecord::PokemonTCG::Card
  end
end

This error still gets raised with the inferred class.

I think this might actually be an outdated documentation issue: the override class isn't specified with klass. Instead, it's specified with the remote_record_class parameter, e.g. remote_record RemoteRecord::PokemonTCG::Card. The documentation needs to be updated to reflect this.