Update openSUSE installation instructions

Out of box, the 'sudo' command on openSUSE does not work similarly to other distros.  In this case, the path to usermod should be explicitly given, since /usr/sbin, where usermod is located, is not on the sudoing user's PATH.  The other sudo commands here should be fine.
Update libcontainer to db65c35051d05f3fb218a0e84a1

Signed-off-by: Michael Crosby <michael@docker.com>
Merge pull request #7634 from krrg/patch-1

Update openSUSE installation instructions
Merge pull request #7648 from crosbymichael/update-libcontainer-aug5

Update libcontainer to db65c35051d05f3fb218a0e84a1
Clean up typos in hub_registry_spec.md

Couple of instances of incorrect articles (e.g. "an Docker Hub").
Automatically relabel volume mounts if user passes :Z with --volume

When you volume mount into a labeled container, we want to allow the
administrator/user the ability to tell docker to fix the labels on the mount.
Using the same basic syntax as the :ro and :rw options on the --volume command

:Z will set the labels so that only the processes within the container can
read/write content.  Since the labels change on creation, this can not be done
by the administrator prior to running the container

:z will change the labels so all containers could read/write content.

drwxr-xr-x. root root system_u:object_r:svirt_sandbox_file_t:s0 /var/run/dan

Docker-DCO-1.1-Signed-off-by: Dan Walsh <dwalsh@redhat.com> (github: rhatdan)