docs: "sender", when paying token transfer fees, needs to be clarified to take allowances into account

[david-bakin-sl]

Documentation at https://docs.hedera.com/hedera/sdks-and-apis/sdks/token-service/custom-token-fees, specifically:

Fixed Fee: Paid by the sender of the fungible or non-fungible tokens. A fixed fee transfers a set amount to a fee collector account each time a token is transferred, independent of the transfer size. This fee can be collected in HBAR or another Hedera token but not in NFTs.

and also any other reference to "sender" does not take into account allowances where the token owner has allowed someone else to send on his behalf.

It can therefore be unexpected that the actual transaction "sender", of a transaction not signed by the token owner, can take fees out of the token owner's account. But what's happening is the actual transaction "sender", having an allowance from the owner, has been authorized by the owner to do so.

Suggest: Documentation be clarified to mention this (and perhaps point to other documentation on allowances/approvals).