(2.13) Add 'access' disk option to man pages
(2.13) Add 'access' disk option to man pages

Update 'gnt-instance' man page and document the 'access' disk option.
Also fix a typo in 'metavg' disk parameter.

Signed-off-by: Ilias Tsitsimpis <7f657306c3c5f1ef1cfa2e11204de3febce40ef6@grnet.gr>
Signed-off-by: Klaus Aehlig <4ce51de36d9068cd7db2eec1151e0f3f95419008@google.com>
Reviewed-by: Klaus Aehlig <4ce51de36d9068cd7db2eec1151e0f3f95419008@google.com>

apyrgio/snf-ganeti,apyrgio/snf-ganeti