Update documentation of new #typed_attributes method to include since flag
Update documentation of new #typed_attributes method to include since flag

Welovroi/mongoid,nviennot/mongoid,kay-kim/mongoid,Sharevari-Inc/mongoid,kay-kim/mongoid,nviennot/mongoid,jonhyman/mongoid,jonhyman/mongoid,mongodb/mongoid,Welovroi/mongoid,mongodb/mongoid,herimedia/mongoid,herimedia/mongoid,mongodb/mongoid,Sharevari-Inc/mongoid