doc: add the right paths to the new pybind modules

Signed-off-by: Alfredo Deza <alfredo.deza@inktank.com>
pybind: warn against using ceph_rest_api module

Signed-off-by: Alfredo Deza <alfredo.deza@inktank.com>
pybind: warn against using ceph_argparse module

Signed-off-by: Alfredo Deza <alfredo.deza@inktank.com>