Add README.md file for the docker directory

See issue #5873

Docker-DCO-1.1-Signed-off-by: Timothy <timothyhobbs@seznam.cz> (github: https://github.com/timthelion)
Add Dinesh Subhraveti to MAINTAINERS

Docker-DCO-1.1-Signed-off-by: Dinesh Subhraveti <dineshs@altiscale.com> (github: dineshs-altiscale)
Docs: add ApiVersion to /version for remote API 1.12

Docker-DCO-1.1-Signed-off-by: Paul Morie <pmorie@gmail.com> (github: pmorie)
Update contrib/check-config.sh to check for CGROUP_FREEZER (which is newly required), and to use /proc/mounts for checking if we have a cgroup hierarchy instead of using /proc/$$/mountinfo (which on systemd might not list the cgroup hierarchy)

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
utils: add test for TimeoutConn

Docker-DCO-1.1-Signed-off-by: Johan Euphrosine <proppy@google.com> (github: proppy)
registry: remove unneeded time.Duration()

These constants don't need to use time.Duration(). Fixup this file since
it seems to be the only one using this style.

Docker-DCO-1.1-Signed-off-by: Brandon Philips <brandon.philips@coreos.com> (github: philips)
Remove the 'TABLE OF CONTENTS' header

Its tricked a number of readers, as its not a TOC, its just local to the
current topic. Now that the docs are not mobile responsive its not an
active UI element either.

Docker-DCO-1.1-Signed-off-by: SvenDowideit <SvenDowideit@home.org.au> (github: SvenDowideit)
Docs: Remove unused font and fix navigation links

Docker-DCO-1.1-Signed-off-by: O.S. Tezer <ostezer@gmail.com> (github: ostezer)
Merge pull request #6285 from ostezer/docs-new-style-improvements

Docs: Remove unused font and fix navigation links
Merge pull request #6264 from SvenDowideit/add-osx-boot2docker-start

add an image to show the use of the Docker OSX applet
Merge pull request #6284 from SvenDowideit/remove-table-of-contents-eyebrow

Remove the 'TABLE OF CONTENTS' header
Initial links

Docker-DCO-1.1-Signed-off-by: James Turnbull <james@lovedthanlost.net> (github: jamtur01)
Merge pull request #6287 from jamtur01/userguide

Initial links
Removed re-appearing production warnings

Docker-DCO-1.1-Signed-off-by: James Turnbull <james@lovedthanlost.net> (github: jamtur01)
Merge pull request #6289 from jamtur01/dev

Removed re-appearing production warnings
Fixed issues in Mac or Windows

Docker-DCO-1.1-Signed-off-by: James Turnbull <james@lovedthanlost.net> (github: jamtur01)
Merge pull request #6291 from jamtur01/mac

Fixed issues in Mac or Windows
Docs: Fix merge issue on docker-hub/builds.md

Docker-DCO-1.1-Signed-off-by: O.S. Tezer <ostezer@gmail.com> (github: ostezer)
fix version numbering

Docker-DCO-1.1-Signed-off-by: Victor Vieux <vieux@docker.com> (github: vieux)
Merge pull request #6292 from ostezer/docs-merge-on-builds

Docs: Fix merge issue on docker-hub/builds.md