Fix example config file
Fix example config file

We need to specify a journal size for the file-based journal we set up
in the example config file.

Signed-off-by: Colin McCabe <c0eabe2887ac1e91c280795b9fca010e21066283@hq.newdream.net>

ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph