Merge pull request #5010 from backstage/rugvip/dockdoc

docs: docker deployment doc updates

docs/getting-started/deployment-docker.md

@@ -15,6 +15,14 @@ are stateless, so for a production deployment you will want to set up and
 connect to an external PostgreSQL instance where the backend plugins can store
 their state, rather than using SQLite.
 
+By default, in an app created with `@backstage/create-app`, the frontend is
+bundled and served from the backend. This is done using the
+`@backstage/plugin-app-backend` plugin, which also injects the frontend
+configuration into the app. This means you that you only need to build and
+deploy a single container in a minimal setup of Backstage. If you wish to
+separate the serving of the frontend out from the backend, see
+[the section on that topic below](#separate-frontend).
+
 ### Host Build
 
 This section describes how to build a Docker image from a Backstage repo with
@@ -224,3 +232,7 @@ Once the `app-backend` is removed from the backend, you can use your favorite
 static file serving method for serving the frontend. An example of how to set up
 an NGINX image is available in the
 [contrib folder in the main repo](https://github.com/backstage/backstage/blob/master/contrib/docker/frontend-with-nginx/Dockerfile)
+
+Note that if you're building a separate docker build of the frontend you
+probably need to adjust `.dockerignore` appropriately. Most likely by making
+sure `packages/app/dist` is not ignored.