More Detailed DB Setup Info

[crystalthoughts]

Hi - the docs on the site are quite basic with regards to the DB setup.

I have a postgres db running already on my docker host on port 5432.

1. How do I change the default windmill database port? Does changing the mapping affect functionality?
2. How does the docker-compose file change when using an external database? Simply setting the replicas to 0 doesn't fix the port conflict.