Values.ButtonSourceDescribes a button to use on a response card used to gather slot values from a user.
type nonrec t = {text : ButtonText.t;The text that appears on the button. Use this to tell the user what value is returned when they choose this button.
*)value : ButtonValue.t;The value returned to Amazon Lex when the user chooses this button. This must be one of the slot values configured for the slot.
*)}