RabbitMQ configuration change

[Cach54]

Hi,

The configuration of rabbitmq seems to be created only the first time of the kickoff run.

To change my rabbitmq credentials via .env and .kickoff.yml, I had to docker volume rm name-of-my-rabbitmq-volume and run kickoff again.

Thank you.

[gulien]

Thank you for your report.

I've updated the documentation (see #27) ! I'll try to update the way the default user and password are created to avoid deleting the volume or using the RabbitMQ dashboard.