In short, it's already linked and being used and displayed in the system. Being able to find it depends on if you used the field.
trxn_date field in the
civicrm_finacial_trxn table stores the receipt date, which shows up in the transaction detail and on the bookkeeping report. If nothing is entered for receipt date, it uses the received date automatically.
Receipt date can be used for when the contributor received the receipt and for when you received the payment, since these should be the same date.
Received Date comes up in the report for date received.
Receipt Date comes up in the report and detail as the transaction date.
I did an experiment in MySQL to make sure this is correct: