Update docs/financial/PaymentAPI.md

Co-Authored-By: Mikey O'Toole <mikey@mjco.uk>

docs/financial/PaymentAPI.md

@@ -11,7 +11,7 @@ It is now best practice to use the Payment.create API call.
 
 Note that paymentprocessor.pay handles the communication with a payment processor to instigate a payment. Similarly, paymentprocessor.refund handles the communication with a payment processor to instigate a refund.
 
-After a contribution has been created, for example using the best practice Order.create api call, use the Payment.create api action to
+After a contribution has been created, for example using the best practice Order.create API call, use the Payment.create API action to
 
 - record a payment against the contribution - either fully or partially paying the contribution amount
 - record a refund against the contribution