Add examples of storage-opts and log-opts for the daemon

[gswallow]

File: engine/reference/commandline/dockerd.md

There are no examples of how to add storage-opts or log-opts, nor anything in second-level lists of properties, really, to /etc/docker/daemon.json. Here's an example that would save a few folks' time.

{
  "storage-driver": "devicemapper",
  "storage-opts": [
    "dm.thinpooldev=/dev/mapper/vg0-pool0",
    "dm.use_deferred_deletion=true",
    "dm.use_deferred_removal=true"
  ],
  "log-driver": "json-file",
  "log-opts": {
    "max-size": "10m",
    "max-file": "10"
  }
}

[scjane]

#dibs

[JimGalasyn]

@scjane How's your progress on this? We'll need to return this to the unclaimed pool for the hackathon, if we don't see a PR. Thanks!

[alvin319]

I'll try to tackle this one!

[alvin319]

I have created a PR in moby to add this example in the documentation.

[mdlinville]

Reviewing upstream. Looks great!