We now return `documents` (for example e-tickets) with orders 📝

Many airlines return "accountable documents" when an order is created. The most common type of document is the e-ticket (electronic_ticket), which represents the fact that the passenger has paid and is entitled to fly on the flights they've booked.

We now return these documents in the API with a type and a unique_identifier. For now, we'll only return e-tickets, with the type electronic_ticket. In the future we may return other kinds of documents like electronic miscellaneous documents (EMDs).

See the Order Schema in our API documentation for more details.