Fix small typo in task name

Change-Id: I80e183985560404455443e6fa22e661bea3c0fa3
Closes-Bug: #1486516

ansible/roles/rabbitmq/tasks/start.yml

 ---
-- name: Starting RabbitMQ bootstrap container
+- name: Starting RabbitMQ container
   docker:
     docker_api_version: "{{ docker_api_version }}"
     net: host