doc/cephadm: add yaml infor for orch apply mon

doc/cephadm: add yaml infor for orch apply mon

This commit breaks one of the long sentences into
three shorter sentences, and adds a parenthetical
comment walking the reader through a series of commands,
explaining what each command does and why only the last
of the commands ends up having a lasting effect on the Ceph
environment.

Fixes: https://tracker.ceph.com/issues/46133
Signed-off-by: Zac Dover <zac.dover@gmail.com>
(cherry picked from commit b02c98bfa5f0ebe442abd97fab16d65b0ebfbf83)