doc: distributed files are under dest

Add the dest path component in the quick start guide instructions for
copying files from a binary OpenAFS distribution file.

Reviewed-on: http://gerrit.openafs.org/7187
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>
(cherry picked from commit bc770a5007ae16aa5477bf1748f3e0666f665781)

Change-Id: I54c96f35ce4f9c60a25fee012306ecb210972287
Reviewed-on: http://gerrit.openafs.org/9564
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>