Line-edit the "Mirroring Module" section of
doc/cephfs/cephfs-mirroring.rst. Add prompts and formatting where such
things contribute to the realization of adequate sentences.
This commit is a follow-up to https://github.com/ceph/ceph/pull/51505.
Co-authored-by: Anthony D'Atri <anthony.datri@gmail.com>
Signed-off-by: Zac Dover <zac.dover@proton.me>