Migration Documentation should state the need for connectivity from controller to brokers when provisioning the KRaft controller quorum

Normal KRaft cluster operations with no nodes configured with process.roles as both controller and broker, there is no need to configure connectivity from the controllers to the brokers. Only brokers need to connect to controllers.

The ZK to KRaft migration does need controller to broker connectivity during the migration and this should be made explicit in the documentation in the Provisioning the KRaft quorum controller section.