I also followed those guides and was puzzled until I realized that it basically means, I don’t need to do anything because my outer NGINX is already taking care of SSL (there is also an inner NGINX running in the docker container but you don’t have to do anything with that one in your setup. Or rather: it doesn’t have to know anything about SSL, which is why you’re supposed to remove "templates/web.ssl.template.yml" from your app.yml).
I’m not sure it’s helpful when I say that you “don’t have to do anything” because of course you have to setup your outer NGINX according to the guide you linked:
But once you’ve done that, you’re fine.
For a better understanding: the discourse.conf becomes part of the nginx.conf and it basically tells NGINX that all traffic going to your discourse forum should also be SSL encrypted.