Clarify first part for the new queue memory page
Clarify first part for the new queue memory page

This might become redundant since we have decided to merge some parts of
this page into `memory-use.xml`

[#151650977]

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