Added copyright/license info required in submissions

git-svn-id: https://nagiosplug.svn.sourceforge.net/svnroot/nagiosplug/nagiosplug/trunk@1276 f882894a-f735-0410-b71e-b25c423dba1c

doc/developer-guidelines.sgml

@@ -649,6 +649,9 @@ update the THANKS.in file.</para>
 	</para>
 
       <orderedlist>
+	<listitem>
+	  <para>Include copyright and license information in all files</para>
+	</listitem>
 	<listitem>
 	  <para>The standard command options are supported (--help, --version,
 	  --timeout, --warning, --critical)</para>