Explicitly call out that we use aes-256 gcm-96 for the barrier.
Explicitly call out that we use aes-256 gcm-96 for the barrier.

Fixes #2913

kingland/vault,Aloomaio/vault,rnaveiras/vault,joelthompson/vault,rnaveiras/vault,hashicorp/vault,hashicorp/vault,mgk/vault,joelthompson/vault,rnaveiras/vault,hartsock/vault,Aloomaio/vault,mgk/vault,hartsock/vault,quixoten/vault,kingland/vault,hartsock/vault,quixoten/vault,mgk/vault,kingland/vault,hashicorp/vault,quixoten/vault,kingland/vault,hashicorp/vault,hashicorp/vault,Aloomaio/vault,Aloomaio/vault,hartsock/vault,joelthompson/vault,kingland/vault,rnaveiras/vault,hashicorp/vault,quixoten/vault,mgk/vault,joelthompson/vault,rnaveiras/vault,hartsock/vault