Add initial docker docs

docker/README-short.txt

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+Docker in Docker!

docker/content.md

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+# What is Docker?
+
+Docker is an open-source project that automates the deployment of applications inside software containers, by providing an additional layer of abstraction and automation of operating-system-level virtualization on Linux, Mac OS and Windows.
+
+> [wikipedia.org/wiki/Docker_(software)](https://en.wikipedia.org/wiki/Docker_%28software%29)
+
+%%LOGO%%
+
+# How to use this image
+
+[![asciicast](https://asciinema.org/a/24707.png)](https://asciinema.org/a/24707)
+
+## start a daemon instance
+
+```console
+$ docker run --privileged --name some-docker -d docker:1.8-dind
+```
+
+**Note:** `--privileged` is required for Docker-in-Docker to function properly, but it should be used with care as it provides full access to the host environment, as explained [in the relevant section of the Docker documentation](https://docs.docker.com/reference/run/#runtime-privilege-linux-capabilities-and-lxc-configuration).
+
+This image includes `EXPOSE 2375` (the Docker port), so standard container linking will make it automatically available to the linked containers (as the following examples illustrate).
+
+## connect to it from a second container
+
+```console
+$ docker run --rm --link some-docker:docker docker:1.7 version
+Client version: 1.7.1
+Client API version: 1.19
+Go version (client): go1.4.2
+Git commit (client): 786b29d
+OS/Arch (client): linux/amd64
+Server version: 1.8.1
+Server API version: 1.20
+Go version (server): go1.4.2
+Git commit (server): d12ea79
+OS/Arch (server): linux/amd64
+```
+
+```console
+$ docker run -it --rm --link some-docker:docker docker:1.8 sh
+/ # docker version
+Client:
+ Version:      1.8.1
+ API version:  1.20
+ Go version:   go1.4.2
+ Git commit:   d12ea79
+ Built:        Thu Aug 13 02:49:29 UTC 2015
+ OS/Arch:      linux/amd64
+
+Server:
+ Version:      1.8.1
+ API version:  1.20
+ Go version:   go1.4.2
+ Git commit:   d12ea79
+ Built:        Thu Aug 13 02:49:29 UTC 2015
+ OS/Arch:      linux/amd64
+```
+
+```console
+$ docker run --rm --link some-docker:docker docker info
+Containers: 0
+Images: 0
+Storage Driver: vfs
+Execution Driver: native-0.2
+Logging Driver: json-file
+Kernel Version: 4.0.9-gentoo
+Operating System: Alpine Linux v3.2 (containerized)
+CPUs: 8
+Total Memory: 31.4 GiB
+Name: 4f19ef15a373
+ID: 3GTC:FH6T:4G5U:7NF4:GM77:JGYU:BOKS:XFCY:H3IQ:JDJ5:X73Z:2K2K
+WARNING: bridge-nf-call-iptables is disabled
+WARNING: bridge-nf-call-ip6tables is disabled
+```
+
+```console
+$ docker run --rm --link some-docker:docker docker:git build https://github.com/docker-library/hello-world.git
+Sending build context to Docker daemon 132.1 kB
+Step 0 : FROM scratch
+ ---> 
+Step 1 : COPY hello /
+ ---> 29bef505052d
+Removing intermediate container f98aab888906
+Step 2 : CMD /hello
+ ---> Running in a735b4037032
+ ---> 3c2b1350a3c4
+Removing intermediate container a735b4037032
+Successfully built 3c2b1350a3c4
+```
+
+```console
+$ docker run --rm -v /var/run/docker.sock:/var/run/docker.sock docker version
+Client:
+ Version:      1.8.1
+ API version:  1.20
+ Go version:   go1.4.2
+ Git commit:   d12ea79
+ Built:        Thu Aug 13 02:49:29 UTC 2015
+ OS/Arch:      linux/amd64
+
+Server:
+ Version:      1.9.0-dev
+ API version:  1.21
+ Go version:   go1.4.2
+ Git commit:   7e3088c-dirty
+ Built:        Tue Aug 18 19:53:53 UTC 2015
+ OS/Arch:      linux/amd64
+```
+
+## custom daemon flags
+
+```console
+$ docker run --privileged --name some-devicemapper-docker -d docker:dind --storage-driver=devicemapper
+```
+
+## Where to Store Data
+
+Important note: There are several ways to store data used by applications that run in Docker containers. We encourage users of the `%%REPO%%` images to familiarize themselves with the options available, including:
+
+-	Let Docker manage the storage of your data [by writing to disk on the host system using its own internal volume management](https://docs.docker.com/userguide/dockervolumes/#adding-a-data-volume). This is the default and is easy and fairly transparent to the user. The downside is that the files may be hard to locate for tools and applications that run directly on the host system, i.e. outside containers.
+-	Create a data directory on the host system (outside the container) and [mount this to a directory visible from inside the container](https://docs.docker.com/userguide/dockervolumes/#mount-a-host-directory-as-a-data-volume). This places the files in a known location on the host system, and makes it easy for tools and applications on the host system to access the files. The downside is that the user needs to make sure that the directory exists, and that e.g. directory permissions and other security mechanisms on the host system are set up correctly.
+
+The Docker documentation is a good starting point for understanding the different storage options and variations, and there are multiple blogs and forum postings that discuss and give advice in this area. We will simply show the basic procedure here for the latter option above:
+
+1.	Create a data directory on a suitable volume on your host system, e.g. `/my/own/var-lib-docker`.
+2.	Start your `%%REPO%%` container like this:
+
+	```console
+	$ docker run --privileged --name some-docker -v /my/own/var-lib-docker:/var/lib/docker -d docker:dind
+	```
+
+The `-v /my/own/var-lib-docker:/var/lib/docker` part of the command mounts the `/my/own/var-lib-docker` directory from the underlying host system as `/var/lib/docker` inside the container, where Docker by default will write its data files.

docker/license.md

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+View [license information](https://github.com/docker/docker/blob/eb7b2ed6bbe3fbef588116d362ce595d6e35fc43/LICENSE) for the software contained in this image.