Core: Change title to be more descriptive

Author: awwright

jsonschema-core.xml

@@ -19,7 +19,7 @@
 <?rfc inline="yes" ?>
 <rfc category="info" docName="draft-wright-json-schema-00" ipr="trust200902">
     <front>
-        <title abbrev="JSON Schema">JSON Schema: core definitions and terminology</title>
+        <title abbrev="JSON Schema">JSON Schema: A Media Type for Describing JSON Documents</title>
 
         <author fullname="Austin Wright" initials="A" surname="Wright" role="editor">
             <address>

jsonschema-hyperschema.xml

@@ -855,7 +855,7 @@ GET /foo/
             &rfc6570;
             <reference anchor="json-schema">
                 <front>
-                    <title>JSON Schema: core definitions and terminology</title>
+                    <title>JSON Schema: A Media Type for Describing JSON Documents</title>
                     <author initials="A." surname="Wright">
                         <organization/>
                     </author>

jsonschema-validation.xml

@@ -776,7 +776,7 @@
             &RFC2119;
             <reference anchor="json-schema">
                 <front>
-                    <title>JSON Schema: core definitions and terminology</title>
+                    <title>JSON Schema: A Media Type for Describing JSON Documents</title>
                     <author/>
                     <date year="2016" month="October"/>
                 </front>