Update jsonschema-core.xml

Co-authored-by: Greg Dennis <[email protected]>

Author: handrews

jsonschema-core.xml

@@ -1297,7 +1297,8 @@
                     <section title="Vocabularies are schema resource-scoped">
                         <t>
                             The "$vocabulary" keyword SHOULD be used in the root schema of any schema
-                            resource intended for use as a meta-schema.  It MUST NOT appear in subschemas.
+                            resource intended for use as a meta-schema.  It MUST NOT appear in subschemas
+                            that are not themselves schema resource roots.
                         </t>
                         <t>
                             The "$vocabulary" keyword MUST be ignored in schema resources that