Fix "Content is not allowed in prolog" warning

One of the javascript examples parcel-descriptor.xml ended up with a c++
comment instead of a xml comment

Change-Id: Ie63a30e19de2caae08e9a489b6592e1046037416

scripting/examples/javascript/Highlight/parcel-descriptor.xml

 <?xml version="1.0" encoding="UTF-8"?>
-/*
+<!--
  * This file is part of the LibreOffice project.
  *
  * This Source Code Form is subject to the terms of the Mozilla Public
@@ -15,7 +15,7 @@
  *   License, Version 2.0 (the "License"); you may not use this file
  *   except in compliance with the License. You may obtain a copy of
  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
- */
+-->
 <parcel language="JavaScript" xmlns:parcel="scripting.dtd">
   <script language="JavaScript">
     <locale lang="en">