MDEV#5759 Init script contains syntax error

Fixed the init script.

support-files/mysql.server.sh

@@ -425,11 +425,15 @@ case "$mode" in
     exit $r
     ;;
   'bootstrap')
+      # Bootstrap the cluster, start the first node
+      # that initiate the cluster
       echo $echo_n "Bootstrapping the cluster"
+      $0 start $other_args --wsrep-new-cluster
+      ;;
   *)
       # usage
       basename=`basename "$0"`
-      echo "Usage: $basename  {start|stop|restart|reload|force-reload|status|configtest}  [ MySQL server options ]"
+      echo "Usage: $basename  {start|stop|restart|reload|force-reload|status|configtest|bootstrap}  [ MySQL server options ]"
       exit 1
     ;;
 esac