doc: improve ceph-mon usage, fix ceph tell examples

The ceph-mon command usage is updated to document all of the ceph-mon
specific options.

The ceph tell usage examples for log and debug are using a deprecated syntax.

Signed-off-by: Loic Dachary <loic@dachary.org>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
doc: fix formatting typo in mon configuration

Signed-off-by: Loic Dachary <loic@dachary.org>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
doc: clarify crush rule create-simple and fix typos

update the description of osd crush rule create-simple using terms that
match the keywords from the crushmap to avoid confusion.

fix missing closing parenthesis in osd crush commands

Signed-off-by: Loic Dachary <loic@dachary.org>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
test: remove zero-copy read_fd test temporarily

This fails since zero-copy from read_fd was temporarily disabled by
03d63c4b2d63b655924c5657637e85abdef40899.

Signed-off-by: Josh Durgin <josh.durgin@inktank.com>