"ChangeLog" not "Change Log" (match the other specs)

Only Hyper-Schema included a space, so get rid of it.

Author: handrews

jsonschema-hyperschema.xml

@@ -2579,7 +2579,7 @@ Link: <https://api.example.com/trees/1/nodes/456> rev=up
             </section>
         </section>
 
-        <section title="Change Log">
+        <section title="ChangeLog">
             <t>
                 <cref>This section to be removed before leaving Internet-Draft status.</cref>
             </t>