LU-13353 quota: add man page for lfs quota

LU-13353 quota: add man page for lfs quota

Add a man page for lfs-quota and remove quota
command from lfs man page. References to quotaon,
quotaoff, and quotacheck are removed because
these subcommands no longer exist.

Test-Parameters: trivial
Signed-off-by: Gian-Carlo DeFazio <defazio1@llnl.gov>
Change-Id: I9321b953e072e7fbb4a5f97f5f9033dd4a3a81dc
Reviewed-on: https://review.whamcloud.com/38183
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Olaf Faaland-LLNL <faaland1@llnl.gov>
Tested-by: Maloo <maloo@whamcloud.com>