doc: Fix typo in ZFS storage
doc: Fix typo in ZFS storage

Signed-off-by: Pavel Sapezhko <0a9e447ef127f7e9f7840dc4a00b85ad68eb7741@gmail.com>

hallyn/lxd,lxc/lxd,stgraber/lxd,hallyn/lxd,hallyn/lxd,lxc/lxd,lxc/lxd,stgraber/lxd,stgraber/lxd,lxc/lxd,lxc/lxd,stgraber/lxd,lxc/lxd,hallyn/lxd,hallyn/lxd,lxc/lxd,stgraber/lxd,stgraber/lxd,stgraber/lxd,hallyn/lxd