Fix title (docker#1056)

The title is not rendered correctly because of the missing newline

Author: whoan

engine/swarm/swarm-tutorial/delete-service.md

@@ -45,6 +45,7 @@ removed the service. The CLI returns a message that the service is not found:
        CONTAINER ID        IMAGE               COMMAND             CREATED             STATUS              PORTS               
 
     ```
+
 ## What's next?
 
 In the next step of the tutorial, you set up a new service and apply a