doc/cephadm: improve "Ceph Daemon Logs" (1 of x)

doc/cephadm: improve "Ceph Daemon Logs" (1 of x)

This PR turned out to be a 3-in-1:

(1) improves syntax and formatting of "Logging to stdout"
(2) improves syntax and formatting of "Logging to files"
(3) replaces all carets with tildes in 3rd-level section
    headers in operations.rst (./build-doc was crying
    about inconsistency when I fed it tildes, but tildes
    and not carets are the RST standard according to
    https://docutils.sourceforge.io/ \
    docs/user/rst/quickstart.html#sections
    so the carets had to go.

Signed-off-by: Zac Dover <zac.dover@gmail.com>