Docs: add ApiVersion to /version for remote API 1.12

Docker-DCO-1.1-Signed-off-by: Paul Morie <pmorie@gmail.com> (github: pmorie)
Add helper function to make prctl system call.
Docker-DCO-1.1-Signed-off-by: Mrunal Patel <mrunalp@gmail.com> (github: mrunalp)
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)
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)
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 #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.
Merge pull request #6438 from jamtur01/opts

Fixed DOCKER_OPTS
Updated Viewing App when on OSX

Added section to show how to get IP address and view running python app if the user is using boot2docker on OSX

Docker-DCO-1.1-Signed-off-by: Richard Harvey <richard@squarecows.com> (github: richarvey)

Docker-DCO-1.1-Signed-off-by: Richard Harvey <richard@squarecows.com> (github: SvenDowideit)
fixup small formatting

Docker-DCO-1.1-Signed-off-by: SvenDowideit <SvenDowideit@home.org.au> (github: SvenDowideit)
Merge pull request #6462 from SvenDowideit/pr_out_fixup_small_formatting

fixup small formatting
exclaimation marks cause shell pain - simplify it away

Docker-DCO-1.1-Signed-off-by: SvenDowideit <SvenDowideit@home.org.au> (github: SvenDowideit)
Merge pull request #6464 from SvenDowideit/pr_out_exclaimation_marks_cause_shell_pain_simplify_it_away

exclaimation marks cause shell pain - simplify it away