contentSchema: type MUST be a schema and instance SHOULD follow the data model

Also changed one other period to be outside its <xref> tag, for consistency.

Author: ssilverman

jsonschema-validation.xml

@@ -530,7 +530,7 @@
                     format attribute and instance SHOULD succeed.  All format attributes defined
                     in this section apply to strings, but a format attribute can be specified
                     to apply to any instance types defined in the data model defined in the
-                    <xref target="json-schema">core JSON Schema.</xref>
+                    <xref target="json-schema">core JSON Schema</xref>.
                     <cref>
                         Note that the "type" keyword in this specification defines an "integer" type
                         which is not part of the data model.  Therefore a format attribute can be
@@ -1023,7 +1023,8 @@
                     JSON Schema's data model.
                 </t>
                 <t>
-                    The value of this property SHOULD be ignored if "contentMediaType" is not present.
+                    The value of this property MUST be a valid JSON schema. It SHOULD be ignored if
+                    "contentMediaType" is not present.
                 </t>
             </section>