Clarify the use of Authorization Details (RAR)

[c2bo]

Section 4.2 states:

MUST use the scope parameter to communicate credential type(s) to be issued. The scope value MUST map to a specific Credential type. The scope value may be pre-agreed, obtained from the Credential Offer, or the Credential Issuer Metadata.

which mandates scopes and does not allow RAR to be used. Later on, section 7.2.4 explains Authorization Details to be used with SD-JWT VCs:

The following additional claims are defined for authorization details of type openid_credential and this Credential format. [..]

We should consider to support RAR (in addition to scopes) which is the path I would prefer or remove the example.