Move zfs options doc to the storage section.
Zfs options belong to the storage section, but they were added under the exec driver section.
@@ -476,8 +476,6 @@ Currently supported options of `devicemapper`:
> Otherwise, set this flag for migrating existing Docker daemons to
> a daemon with a supported environment.
-### Docker execdriver option
-
Currently supported options of `zfs`:
* `zfs.fsname`
@@ -490,6 +488,8 @@ Currently supported options of `zfs`:
$ docker -d -s zfs --storage-opt zfs.fsname=zroot/docker
+### Docker execdriver option
+
The Docker daemon uses a specifically built `libcontainer` execution driver as
its interface to the Linux kernel `namespaces`, `cgroups`, and `SELinux`.
