Change the domain statement of "holder"

Remove the VerifiableCredential from the possible domains of holder. This is the "execution" of #1076 (comment).

Beware! This is a PR against the OR13-remove-holder-from-vc PR, not against the main branch!

Author: iherman

vocab/credentials/v2/vocabulary.yml

@@ -93,9 +93,7 @@ property:
 
   - id: holder
     label: Holder
-    domain:
-      - cred:VerifiableCredential
-      - cred:VerifiablePresentation
+    domain: cred:VerifiablePresentation
     range : IRI
     comment: |
       The value of the `holder` property MUST be a URI. It is RECOMMENDED that dereferencing the URI results in a document containing machine-readable information about the holder that can be used to verify the information expressed in the credential.