Add data-model anchor.

Author: ioggstream

jsonschema-core.xml

@@ -210,7 +210,7 @@
                     media type which defines handling for fragments in the IRI.
                 </t>
 
-                <section title="Instance Data Model">
+                <section title="Instance Data Model" anchor="data-model">
                     <t>
                         JSON Schema interprets documents according to a data model. A JSON value
                         interpreted according to this data model is called an "instance".