correct port in docker-compose.yml

[asayake-b5]

Hello,

I was struggling to make the app run, until I realized from the docs that the host port was wrong, I assume it changed in the 2 years since the last update. So I figured I'd PR to save other people the potential trouble.

I'm not sure why there's a second change in my commit, github seems to randomly add it even though there's no actual change if we do compare the two files.

Thanks for your work :)