Mention that full cluster stop is required for minor upgrades.
Mention that full cluster stop is required for minor upgrades.

Upgrade compatibility table can be confusing for people planning
the rolling upgrade. Make it clear that the table is for full-stop
upgrades only.

[#157732962]

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