Fix bash completion for `--log-opt mode`

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

contrib/completion/bash/docker

@@ -790,7 +790,7 @@ __docker_complete_log_driver_options() {
 			return
 			;;
 		mode)
-			COMPREPLY=( $( compgen -W "blocking nonblocking" -- "${cur##*=}" ) )
+			COMPREPLY=( $( compgen -W "blocking non-blocking" -- "${cur##*=}" ) )
 			return
 			;;
 		syslog-address)