Fix grammar

Author: Relequestual

jsonschema-core.xml

@@ -1858,7 +1858,7 @@
                     </t>
                     <t>
                         When the Schema Resource referenced by a by-reference applicator is bundled, the Schema Resource
-                        MUST be located as a value of a "$defs" object at the containing schemas root.
+                        MUST be located as a value of a "$defs" object at the containing schema's root.
                         The key of the "$defs" for the now embedded Schema Resource MAY be the "$id" of the bundled schema
                         or some other form of application defined unique identifer (such as a UUID). This key is not
                         intended to be referenced in JSON Schema, but may be used by an application to aid the