Merge pull request #917 from ssilverman/shawn/contentSchema

contentSchema: type MUST be a schema

Author: handrews

jsonschema-validation.xml

@@ -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>