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)
Docker Docs styling overhaul

This commit/PR changes docs' styling with Docker general styling

Docker-DCO-1.1-Signed-off-by: O.S. Tezer <ostezer@gmail.com> (github: ostezer)
Update dockervolumes.md

Error on title note :)
Merge pull request #6279 from sebastienhouzet/patch-3

Update dockervolumes.md
Update dockerizing.md
Merge pull request #6280 from jobrieniii/patch-1

Update dockerizing.md
Update usingdocker.md

Just noticed `sudo` missing on line 232.  (Learning so doing lots of copying / pasting)
Merge pull request #6275 from ostezer/docs-design-dev

Docker Docs styling overhaul
Merge pull request #6281 from jobrieniii/patch-2

Update usingdocker.md
Update usingdocker.md

Added container name `nostalgic_morse` to end of `inspect -f` example
Merge pull request #6282 from jobrieniii/patch-3

Update usingdocker.md
Videos for installing b2d

Mac and Windows video embeds from YouTube

Docker-DCO-1.1-Signed-off-by: Aaron Huslage <huslage@gmail.com> (github: huslage)
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)
Merge pull request #6283 from huslage/doc-videos

Videos for installing b2d
add an image to show the use of the Docker OSX applet

Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@docker.com> (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)