Development docs warning for beta-docs.docker.io

Update: Fix alignment issues of the "warning" block.

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

Docker-DCO-1.1-Signed-off-by: O.S.Tezer <ostezer@gmail.com> (github: SvenDowideit)
make the non-release doc warning conditional and add version info

use the beta-warning area to tell the user what VERSION of docker, git
branch, and links to the official release version docs are.

requires / extends PR #5272

Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@fosiki.com> (github: SvenDowideit)
Merge pull request #5337 from tianon/man1-assumption

Update contributed man page file names and compilation script
devicemapper: Don't mount in Create()

We used to mount in Create() to be able to create a few files that
needs to be in each device. However, this mount is problematic for
selinux, as we need to set the mount label at mount-time, and it
is not known at the time of Create().

This change just moves the file creation to first Get() call and
drops the mount from Create(). Additionally, this lets us remove
some complexities we had to avoid an extra unmount+mount cycle.

Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)
Merge pull request #5351 from SvenDowideit/docs-conditional-beta-warning

Docs conditional beta warning
avoid suicide

container.Kill() might read a pid of 0 from
container.State.Pid due to losing a race with
container.monitor() calling
container.State.SetStopped(). Sending a SIGKILL to
pid 0 is undesirable as "If pid equals 0, then sig
is sent to every process in the process group of
the calling process."

Docker-DCO-1.1-Signed-off-by: Daniel Norberg <daniel.norberg@gmail.com> (github: danielnorberg)
Merge pull request #5336 from tianon/slightly-more-organized-check-config

Move "possible config locations" list to the top of check-config.sh
Remove error from engine.New()

Without creating a root there is no way for the engine to return an
error from the new function.
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Update link to interactive tutorial
Update link to interactive tutorial
Add exported status code from a job

This allows the job's status code to be consumed externally so that we
can use it as an exit code or saving to a state file.
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)
Merge pull request #5347 from crosbymichael/engine-root

Remove root dir from engine
Merge pull request #5345 from shykes/engine-installer

engine.Installer: a standard interface for "installable" services
Merge pull request #5349 from ipbabble/manpages

Manpages - fixes and merged tianon/docker man1-assumption branch
 - unix://path/to/socket should read unix:///path/to/socket like the rest of the documentation (a slash was missing)
 - Mention that [] options may be specified multiple times on the Usage page

Docker-DCO-1.1-Signed-off-by: Mike MacCana <mike.maccana@gmail.com> (github: mikemaccana)

Docker-DCO-1.1-Signed-off-by: Mike MacCana <mike.maccana@gmail.com> (github: SvenDowideit)
add a reference to multiple -H options, and update the other example of -H option

and copy changes to the cli.md file

Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@fosiki.com> (github: SvenDowideit)
Merge pull request #5362 from sindhus/patch-2

Update link to interactive tutorial
Docs: Add docs new version files created by `make docs` to .gitignore

Files are:

 - docs/AWS_S3_BUCKET
 - docs/GIT_BRANCH
 - docs/VERSION

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

Update:

 - Remove unnecessary last blankline
Docs auto-conversion fixes and MD marking and structure improvements.

 - Remove redundant chars and all errors caused by RST->MD conversion.
   e.g. [/#, /\, \<, />, etc.]
 - Fix broken inter-document links
 - Fix outbound links no-longer active or changed
 - Fix lists
 - Fix code blocks
 - Correct apostrophes
 - Replace redundant inline note marks for code with code marks
 - Fix broken image links
 - Remove non-functional title links
 - Correct broken cross-docs links
 - Improve readability

Note: This PR does not try to fix/amend:

 - Grammatical errors
 - Lexical errors
 - Linguistic-logic errors etc.

It just aims to fix main structural or conversion errors to serve as
a base for further amendments that will cover others including but
not limited to those mentioned above.

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

Update:

 - Fix backtick issues

Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@home.org.au> (github: SvenDowideit)
Looking into some broken links, I noticed that we don't need to use
relative paths, and also fixed some broken images.

There are still more todo - next PR I think :)

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