fix error in the wallet definition (#164)

editorial. 8 approvals.

* fix error in the wallet definition

* clarify issuer can be RS or AS

Co-authored-by: Giuseppe De Marco <demarcog83@gmail.com>

* remove rfc6749 reference

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Co-authored-by: Kristina <=>
Co-authored-by: Giuseppe De Marco <demarcog83@gmail.com>

openid-4-verifiable-credential-issuance-1_0.md

@@ -103,7 +103,7 @@ Biometrics-based Holder Binding:
 :  Ability of the Holder to prove legitimate possession of a Verifiable Credential by demonstrating a certain biometric trait, such as fingerprint or face. One example of a Verifiable Credential with Biometrics-based Holder Binding is a mobile driving license [@ISO.18013-5], which contains a portrait of the holder.
 
 Wallet:
-:  An entity used by the Holder to receive, store, present, and manage Verifiable Credentials and key material. There is no single deployment model of a Wallet: Verifiable Credentials and keys can both be stored/managed locally, or by using a remote self-hosted service, or a remote third-party service. In the context of this specification, the Wallet acts as an OAuth 2.0 Authorization Server (see [@!RFC6749]) towards the Credential Verifier which acts as the OAuth 2.0 Client.
+:  An entity used by the Holder to request, receive, store, present, and manage Verifiable Credentials and key material. There is no single deployment model of a Wallet: Verifiable Credentials and keys can both be stored and managed locally, or by using a remote self-hosted service, or a remote third-party service. In the context of this specification, the Wallet acts as an OAuth 2.0 Client since the Credential Issuer is the OAuth 2.0 Resource Server and, in certain cases, it may also implement an OAuth 2.0 Authorization Server.
 
 Deferred Credential Issuance:
 :  Issuance of Credentials not directly in the response to a Credential issuance request but following a period of time that can be used to perform certain offline business processes.