RFC 0511 - Missing transition in 0453 from Receive request-credential to Send offer-credential

[RFC 0511](https://github.com/hyperledger/aries-rfcs/blob/master/features/0511-dif-cred-manifest-attach/README.md) currently says:
> This allows the Holder to initiate the issue-credential protocol with a request-message providing they also possess the requisite challenge and domain values. If they do not possess these values then the Issuer MAY respond with an offer-credential message.

The state machine in [RFC 0453](https://github.com/hyperledger/aries-rfcs/tree/master/features/0453-issue-credential-v2) does not have a transition from `Receive request-credential` to `Send offer-credential`.