Missed a xref change to $anchor

Author: handrews

jsonschema-core.xml

@@ -479,7 +479,7 @@
             <t>
                 Defining and referencing a plain name fragment identifier within an
                 "application/schema+json" document are specified
-                in the <xref target="id-keyword">"$id" keyword</xref> section.
+                in the <xref target="anchor">"$anchor" keyword</xref> section.
             </t>
             <t>
             </t>