ceph: add not about filesystems for Ceph cluster
ceph: add not about filesystems for Ceph cluster

This affects the storage entities that are used to form OSD storage pools not
the RBD storage volumes themselves.

Signed-off-by: Christian Brauner <48455ab3070520a2d174545c7239d6d0fabd9a83@ubuntu.com>

Skarlso/lxd,hallyn/lxd,erikmack/lxd,mjeanson/lxd,pcdummy/lxd,stgraber/lxd,erikmack/lxd,Skarlso/lxd,jsavikko/lxd,stgraber/lxd,atxwebs/lxd,jsavikko/lxd,lxc/lxd,hallyn/lxd,Skarlso/lxd,lxc/lxd,hallyn/lxd,lxc/lxd,hallyn/lxd,hallyn/lxd,pcdummy/lxd,atxwebs/lxd,Skarlso/lxd,hallyn/lxd,lxc/lxd,stgraber/lxd,stgraber/lxd,erikmack/lxd,stgraber/lxd,stgraber/lxd,pcdummy/lxd,mjeanson/lxd,lxc/lxd,lxc/lxd,lxc/lxd,stgraber/lxd,mjeanson/lxd,atxwebs/lxd,jsavikko/lxd,atxwebs/lxd