Update documentation for 2.3.0/2.3.1 added fields

Change-Id: Iac660ec5fa63a5085c4febb8b34e96ec688594a8
Reviewed-on: http://review.couchbase.org/36582
Reviewed-by: Mark Nunberg <mnunberg@haskalah.org>
Tested-by: Mark Nunberg <mnunberg@haskalah.org>