update credentialSchema id to align with spec text (#242)

Author: mkhraisha

schema/json-schema-credential-schema.json

@@ -42,7 +42,7 @@
       "properties": {
         "id": {
           "type": "string",
-          "const": "https://www.w3.org/2022/credentials/v2/json-schema-credential-schema.json"
+          "const": "https://www.w3.org/ns/credentials/json-schema/v2.json"
         },
         "type": {
           "type": "string",