add methods

Author: PrenSJ2

pages/proforma-invoices/take-proforma-invoice-payment.md

@@ -1,4 +1,4 @@
 ### Take Proforma Invoice Payment
 
 Pay partially or pay in full, post how much the Client paid towards the Proforma Invoice and we'll return how much there is
-`still_to_pay`. If fully paid off, `paid` will return a value of `true`.
+`still_to_pay`. If fully paid off, `paid` will return a value of `true`. `method` is used to define the offline payment method used the choices are `cash`, `cheque`, `credit_card`, `bonus_credit`, `manual`, `voucher`.