Improve warning message about code being auto-generated

Change-Id: I9b5460ed09ed458f86e4ea3001f73e482ef97765
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>

src/designer/data/generate_header.xsl

@@ -383,7 +383,7 @@
 // We mean it.
 //
 
-// THIS FILE IS AUTOMATICALLY GENERATED
+// THIS FILE IS AUTOMATICALLY GENERATED. DO NOT EDIT!
 
 #ifndef UI4_H
 #define UI4_H

src/designer/data/generate_impl.xsl

@@ -941,6 +941,9 @@
 ** $QT_END_LICENSE$
 **
 ****************************************************************************/
+
+// THIS FILE IS AUTOMATICALLY GENERATED. DO NOT EDIT!
+
 </xsl:text>
         <xsl:text>#include "ui4_p.h"&endl;</xsl:text>
         <xsl:text>&endl;</xsl:text>