doc: vos manpage fixes

doc: vos manpage fixes

 - Add missing -config option to 'common' vos options, and to the
   synopsis for all commands

 - Remove brackets in the options descriptions for vos_shadow,
   vos_create, and vos_clone. We don't do this in other manpages.

 - vos_create: Add missing -id, -roid to synopsis

 - vos_clone: Add missing -readwrite option

 - vos_shadow: Add missing -toid option

Change-Id: I41fd56509e78116698c82a2f3f4fd07f26cdc95f
Reviewed-on: http://gerrit.openafs.org/10397
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>