Docs: add ApiVersion to /version for remote API 1.12

Docker-DCO-1.1-Signed-off-by: Paul Morie <pmorie@gmail.com> (github: pmorie)
Don't exit on eof in header reading in stdcopy

There was random lines drops in docker logs because of this
Docker-DCO-1.1-Signed-off-by: Alexandr Morozov <lk4d4math@gmail.com> (github: LK4D4)
Increase time before exit in TestMultipleAttachRestart

Sometimes third attacher attaching to already stopped container.
Also I've changed prefix to attach and fixed cleanup on Fatal.
Docker-DCO-1.1-Signed-off-by: Alexandr Morozov <lk4d4math@gmail.com> (github: LK4D4)
Add helper function to make prctl system call.
Docker-DCO-1.1-Signed-off-by: Mrunal Patel <mrunalp@gmail.com> (github: mrunalp)
Fix several man page spelling errors

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Do inspect under container lock

It fixes some race conditions
Docker-DCO-1.1-Signed-off-by: Alexandr Morozov <lk4d4math@gmail.com> (github: LK4D4)
Fixed DOCKER_OPTS

Docker-DCO-1.1-Signed-off-by: James Turnbull <james@lovedthanlost.net> (github: jamtur01)
Updated docker pull manpage to reflect ability to specify URL of registry.

Also fixed a typo in same file.

Docker-DCO-1.1-Signed-off-by: Matthew Heon <mheon@redhat.com> (github: mheon)
Merge pull request #6425 from tianon/fix-man-page-spelling-errors

Fix several man page spelling errors
Updated CLI documentation for docker pull with notes on specifying URL

Docker-DCO-1.1-Signed-off-by: Matthew Heon <mheon@redhat.com> (github: mheon)
Issue #5279 -> Introduce horizontal scrolling to code-blocks

Closes issue #5279

This commit re-introduces horizontal scrolling to docs' codeblocks

Docker-DCO-1.1-Signed-off-by: O.S. Tezer <ostezer@gmail.com> (github: ostezer)
Document the potential insecurity of --net host

Docker-DCO-1.1-Signed-off-by: Timothy <timothyhobbs@seznam.cz> (github: https://github.com/timthelion)
Issue #5036 -> Click on nav bar goes to top level doc

Closes issue #5036

This commit redirects the reader to top level doc upon clicking
on a main nav. menu item (eg. Installation [click] -> Mac OS X)

Docker-DCO-1.1-Signed-off-by: O.S. Tezer <ostezer@gmail.com> (github: ostezer)
Merge pull request #6458 from ostezer/docs-code-block-scrolling

Issue #5279 -> Introduce horizontal scrolling to code-blocks
Merge pull request #6430 from LK4D4/lock_inspect

Do inspect under container lock
Merge pull request #6449 from timthelion/host-net-docs

Document the potential insecurity of --net host
Merge pull request #6459 from ostezer/issue-5036-main-nav-top-level-click

Issue #5036 -> Click on nav bar goes to top level doc
Merge pull request #6306 from mheon/fix_manpage_issue

Update documentation for docker pull
Merge pull request #6240 from pmorie/docs

Add ApiVersion to doc example for remote API 1.12 /version
Merge pull request #6417 from mrunalp/dev/system_prctl

Add helper function to make prctl system call.