Fix Syntax highlighting for Kate

Apparently Kate requires the <itemDatas> to be inside the <highlighting>
tag whereas QtCreator also accepts it a level higher.

Tested using this DTD:
https://github.com/jgm/highlighting-kate/blob/master/xml/language.dtd

highlighting/qtcreator/capnp.xml

@@ -106,7 +106,6 @@
         <RegExpr attribute="Annotation" context="#stay" String="'([^'\\]|\\.)*'"/>
       </context>
     </contexts>
-  </highlighting>
     <itemDatas>
       <!-- Since my highlighting approach is different from most programming languages, the contexts
           don't fit nicely into the standard set, so I have to define colors explicitly.  A couple
@@ -125,6 +124,7 @@
       <itemData name="Comment"      defStyleNum="dsComment"/>
       <itemData name="Symbol"       defStyleNum="dsOthers" bold="1"/>
     </itemDatas>
+  </highlighting>
   <general>
     <comments><comment name="singleLine" start="#"/></comments>
     <keywords casesensitive="1"/>