adding details about port choice with AWS SG

machine/examples/aws.md

@@ -93,6 +93,8 @@ Follow along with this example to create a Dockerized <a href="https://aws.amazo
 
     Start with something basic like `docker run hello-world`, or for a more interesting test, run a Dockerized webserver on your new remote machine.
 
+    **Note**: We are using port `8000` in this example and that port has been added to the AWS Security Group associated with docker-machine. If you want to run your container on another port, you will need to update the security group to reflect that.
+
     In this example, the `-p` option is used to expose port 80 from the `nginx` container and make it accessible on port `8000` of the `aws-sandbox` host.
 
         $ docker run -d -p 8000:80 --name webserver kitematic/hello-world-nginx
@@ -122,4 +124,4 @@ To remove an instance and all of its containers and images, first stop the machi
 -   [Understand Machine concepts](../concepts.md)
 -   [Docker Machine driver reference](../drivers/index.md)
 -   [Docker Machine subcommand reference](../reference/index.md)
--   [Provision a Docker Swarm cluster with Docker Machine](/swarm/provision-with-machine.md)
+-   [Provision a Docker Swarm cluster with Docker Machine](/swarm/provision-with-machine.md)