docs: update example lustre client mount; previous variant not working
consistently with latest version and centos7.5.
# Include mount point and file system mount in compute image
[sms](*\#*) mkdir $CHROOT/mnt/lustre
-[sms](*\#*) echo "${mgs_fs_name} /mnt/lustre lustre defaults,_netdev,localflock,retry=2 0 0" >> $CHROOT/etc/fstab
+[sms](*\#*) echo "${mgs_fs_name} /mnt/lustre lustre defaults,localflock,noauto,x-systemd.automount 0 0" \
+ >> $CHROOT/etc/fstab
\end{lstlisting}
% end_ohpc_run
