xml add gnome wallpaper to library code example

Example: xml gnome wallpaper

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE wallpapers SYSTEM "gnome-wp-list.dtd">
<wallpapers>
	<wallpaper deleted="false">
    	<name>Wallpaper Name</name>
        <filename>Path/To/Image</filename>
        <options>zoom</options>
   	</wallpaper>
</wallpapers>