Bug: SIP-005 states that stx transfer transaction can't be sponsored

[friedger]

SIP-005 states:

Note that if a transaction contains a token-transfer payload, it MUST
have only a standard authorization field. It cannot be sponsored.

https://github.com/stacksgov/sips/blob/e567447f53bca3b980546de26746208dcaeab7c5/sips/sip-005/sip-005-blocks-and-transactions.md?plain=1#L664C1-L665C65

However, the chain confirms a sponsored stx transfer:

The motivation for the specification in SIP 5 is not clear and the chain works without the specified restriction on sponsored transaction. Therefore, the specification should be adjusted and the paragraph removed.