Description of problem:

In the current README, we are instructing users to uncomment the db service block in the default compose.yaml file: https://github.com/redhat-developer/rhdh-local/blob/main/README.md#using-a-postgresql-database

I think it should be possible to accomplish this without the need to modify the default compose.yaml file, but via a separate compose-with-db.yaml file, similar to compose-with-corporate-proxy.yaml or compose-dynamic-plugins-root.yaml.

This way, users who want a PostgreSQL database could run:

podman compose up -f compose.yaml -f compose-with-db.yaml -d