Fix markup. s/DestinationAmount/DeliveredAmount/

DestinationAmount is actually `DeliveredAmount` and (for better or worse) is set only when the full amount wasn't paid.

if (rc.result () == tesSUCCESS && rc.actualAmountOut != saDstAmount)
    mEngine->view ().setDeliveredAmount (rc.actualAmountOut);

References: https://github.com/ripple/rippled/blob/2936bbfae86de2c94d5a1ee6ac129dd4f92de870/src/ripple/app/transactors/Payment.cpp#L292
https://github.com/ripple/rippled/blob/2936bbfae86de2c94d5a1ee6ac129dd4f92de870/src/ripple/data/protocol/SField.h#L358