Move ZFS options to correct place in man page

Signed-off-by: Zhu Guihua <zhugh.fnst@cn.fujitsu.com>

man/docker-daemon.8.md

@@ -465,16 +465,6 @@ this topic, see
 Otherwise, set this flag for migrating existing Docker daemons to a
 daemon with a supported environment.
 
-## ZFS options
-
-#### zfs.fsname
-
-Set zfs filesystem under which docker will create its own datasets.
-By default docker will pick up the zfs filesystem where docker graph
-(`/var/lib/docker`) is located.
-
-Example use: `docker daemon -s zfs --storage-opt zfs.fsname=zroot/docker`
-
 #### dm.min_free_space
 
 Specifies the min free space percent in thin pool require for new device
@@ -499,6 +489,16 @@ that should resolve the issue.
 
 Example use: `docker daemon --storage-opt dm.min_free_space_percent=10%`
 
+## ZFS options
+
+#### zfs.fsname
+
+Set zfs filesystem under which docker will create its own datasets.
+By default docker will pick up the zfs filesystem where docker graph
+(`/var/lib/docker`) is located.
+
+Example use: `docker daemon -s zfs --storage-opt zfs.fsname=zroot/docker`
+
 # CLUSTER STORE OPTIONS
 
 The daemon uses libkv to advertise