Fix copy/paste typos in MQTT plugin doc
Fix copy/paste typos in MQTT plugin doc

Co-authored-by: George Blue <eb84c35f2b1b4e421f04f3b8239bc4d268cca455@pivotal.io>

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