Clarify the source of truth that the data access API works upon.

[nuttycom]

The data access api provides a view over on-chain data that is relevant to a particular wallet. One current limitation is that if outgoing data from a wallet is encrypted to a custom OCK, the wallet may not detect the outgoing notes when scanning the chain. Should the data access API be expanded to manage information that the wallet has knowledge of, but which may not be recoverable from the chain?