x-quorum-cluster-size was renamed to x-quorum-initial-group-size
x-quorum-cluster-size was renamed to x-quorum-initial-group-size

before 3.8.0 GA shipped but we have never updated
the docs.

rabbitmq/rabbitmq-website,rabbitmq/rabbitmq-website,rabbitmq/rabbitmq-website,rabbitmq/rabbitmq-website,rabbitmq/rabbitmq-website