edina/fieldtrip-cobweb#2: added link to the button of layers
edina/fieldtrip-cobweb#2: added link to the button of layers

edina/fieldtrip-cobweb-project,cobweb-eu/fieldtrip-cobweb-project,edina/fieldtrip-cobweb-project,cobweb-eu/fieldtrip-cobweb-project