Add bash completion for `{stack services,service ls} --format`

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

contrib/completion/bash/docker

@@ -2850,11 +2850,14 @@ _docker_service_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
 }
@@ -3895,14 +3898,17 @@ _docker_stack_services() {
 			__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" ) )
 			;;
 		*)
-			local counter=$(__docker_pos_first_nonflag '--filter|-f')
+			local counter=$(__docker_pos_first_nonflag '--filter|-f|--format')
 			if [ $cword -eq $counter ]; then
 				__docker_complete_stacks
 			fi