doc: correct implicit ACL permissions volume owner

doc: correct implicit ACL permissions volume owner

OpenAFS changed the behavior of implicit administrator permission
for directory ownership.  In OpenAFS only the volume root directory
owner has implicit administrator permissions and they apply to all
directories in the volume not just those with matching ownership.

Reviewed-on: http://gerrit.openafs.org/6951
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>
(cherry picked from commit 95ec152a850c0cde33829481b8e71e7e7e686a58)

Change-Id: I390e11fcf64b7cdb192e49e0967b7890e831ea45
Reviewed-on: http://gerrit.openafs.org/6954
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>
Tested-by: Jeffrey Altman <jaltman@secure-endpoints.com>