message: docs/deployment: note that separate frontend is optional
diff: @@ -275,6 +275,11 @@ browser at `http://localhost:7007`
  ## Separate Frontend
  +> NOTE: This is an optional step, and you will lose out on the features of the
  +> `@backstage/plugin-app-backend` plugin. Most notably the frontend configuration
  +> will no longer be injected by the backend, you will instead need to use the
  +> correct configuration when building the frontend bundle.
  +
  It is sometimes desirable to serve the frontend separately from the backend,
  either from a separate image or for example a static file serving provider. The
  first step in doing so is to remove the `app-backend` plugin from the backend
  