Also update oidc_scope_prefix description in config_schema.yml

lib/galaxy/config/schemas/config_schema.yml

@@ -2910,7 +2910,11 @@ mapping:
         desc: |
           Sets the prefix for OIDC scopes specific to this Galaxy instance.
           If an API call is made against this Galaxy instance using an OIDC bearer token,
-          it must include a scope with "<prefix>:*". e.g "https://galaxyproject.org/api:*"
+          any scopes must be prefixed with this value e.g. https://galaxyproject.org/api.
+          More concretely, to request all permissions that the user has, the scope
+          would have to be specified as "<prefix>:*". e.g "https://galaxyproject.org/api:*".
+          Currently, only * is recognised as a valid scope, and future iterations may
+          provide more fine-grained scopes.
 
       auth_config_file:
         type: str