Feature/update port

[CarlSargunar]

Fix for https://github.com/docker/getting-started/issues/267

This will set the default instructions which will allow windows users who are web developers, and therefore likely to be running IIS which uses port 80.

Added some additional info as to why these ports are used, but open to suggestions on how to word this.

Please note - I also had to make the changes suggested in https://github.com/docker/getting-started/issues/257 to get a local image to build locally, but I have not submitted those changes as part of this PR, since they are not related

[pmario]

Hi, I did have the same problem and thought I'll have a look and create a PR. I found your issue.

I think instead of changing the port to 9080 it should stay as it is. I think having access to localhost is much more impressive than localhost:9080

BUT I think an explanation should be there, if an error is thrown on Windows, it is likely because IIS is using it already. ... IMO the explanation should be enough.

just some thoughts.