Documentation: Postgres installation

[zopyx]

Perhaps you could add a section to installation notes how to install Websauna with a Dockerized
Postgres installation for the sake of making the initial setup less painless. Although the Postgres installation and setup is not that hard but it requires some manual steps. A setup with a well-defined Postgres Docker image might help here.

[miohtama]

I'd love to. However I have zero Docker experience. I have only once during my life time run docker run command.

Furthermore the developer needs Redis, not just Docker. So this could be in the same image.