Merge pull request #1273 from ioggstream/ioggstream-xref-1

Add data-model anchor.

Author: handrews

jsonschema-core.xml

@@ -187,7 +187,7 @@
                 </t>
                 <t>
                     In JSON Schema, the terms "JSON document", "JSON text", and "JSON value" are
-                    interchangeable because of the data model it defines.
+                    interchangeable because of the data model it defines in <xref target="data-model" />.
                 </t>
                 <t>
                     JSON Schema is only defined over JSON documents. However, any document or memory
@@ -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".