document api response from POST,PUT and DELETE not only GET.
i.e. on successful Contacts POST returned xml will be: <write>returned xml here</write>
while on failure, depending on the cause, the following errors can be returned:<error> possible error here</error>
And so on for all the methods in Contacts, Invoices etc.
Currently only the GET responses are documented.
This old issue has been fully addressed, but please feel free to let us know if there are any more documentation issues you spot.