Mention Raft log segment change in 3.8.4 release notes
Mention Raft log segment change in 3.8.4 release notes

Per discussion with @kjnilsson.
Reported by @mkuratczyk.

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