Add bash completion for `service ls --filter mode`

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

contrib/completion/bash/docker

@@ -2868,6 +2868,10 @@ _docker_service_ls() {
 			__docker_complete_services --cur "${cur##*=}" --id
 			return
 			;;
+		mode)
+			COMPREPLY=( $( compgen -W "global replicated" -- "${cur##*=}" ) )
+			return
+			;;
 		name)
 			__docker_complete_services --cur "${cur##*=}" --name
 			return
@@ -2876,7 +2880,7 @@ _docker_service_ls() {
 
 	case "$prev" in
 		--filter|-f)
-			COMPREPLY=( $( compgen -W "id label name" -S = -- "$cur" ) )
+			COMPREPLY=( $( compgen -W "id label mode name" -S = -- "$cur" ) )
 			__docker_nospace
 			return
 			;;