Add a link to blu green upgrade
Add a link to blu green upgrade

Signed-off-by: Gabriele Santomaggio <f9ece1c195334350f2f2cbad0407d81fd8628854@gmail.com>

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