[cluster] Fix the help option

projects/cluster/docker-cluster-up.sh

@@ -36,11 +36,12 @@ usage() {
   exit 1
 }
 
-OPTS=$(getopt -o fi:n:p:w: --long force,image:,name:,port:,workdir:,no-pull -n "$0" -- "$@") || usage
+OPTS=$(getopt -o hfi:n:p:w: --long help,force,image:,name:,port:,workdir:,no-pull -n "$0" -- "$@") || usage
 eval set -- "${OPTS}"
 
 while true; do
   case "$1" in
+    -h|--help)       usage ;;
     -f|--force)      FORCE_RM=1; shift ;;
     -i|--image)      IMAGE_NAME="$2"; shift 2 ;;
     -n|--name)       CONTAINER_NAME="$2"; shift 2 ;;