Update Netsuite Finance 2016 Documentation to Include PO Status Queryable Fields

[brotaylo]

Description

Netsuite Finance 2016 GET /purchase-orders accepts query by purchase order (PO) Status, but there is customer confusion because a GET over purchase-orders is only query-able using the Netsuite transaction status values (e.g. _purchaseOrderClosed) and not the status values returned in the Response Body (e.g. Closed). The full list of purchase order transaction statuses can be found here: http://www.netsuite.com/help/helpcenter/en_US/srbrowser/Browser2016_2/schema/enum/transactionstatus.html?mode=package

We need to add a reference to these queryable purchase order status values in our documentation for better client visibility.

Thank you, Brody

Soba Issue

This is related to the soba issue #6861.