Add bash completion for `node ls --format`

Signed-off-by: Harald Albers <github@albersweb.de>

contrib/completion/bash/docker

@@ -3472,11 +3472,14 @@ _docker_node_ls() {
 			__docker_nospace
 			return
 			;;
+		--format)
+			return
+			;;
 	esac
 
 	case "$cur" in
 		-*)
-			COMPREPLY=( $( compgen -W "--filter -f --help --quiet -q" -- "$cur" ) )
+			COMPREPLY=( $( compgen -W "--filter -f --format --help --quiet -q" -- "$cur" ) )
 			;;
 	esac
 }