update document

Signed-off-by: Gabriel Dantas <gabriel.dantas98@outlook.com.br>

docs/deployment/heroku.md

@@ -18,11 +18,10 @@ First, install the
 $ heroku login
 ```
 
-Heroku runs a container registry on `registry.heroku.com`. To push Backstage
-Docker images, log in to the container registry also:
+If you have not yet created a project through the Heroku interface, you can create it through the CLI.
 
 ```shell
-$ heroku container:login
+$ heroku create <your-app>
 ```
 
 You _might_ also need to set your Heroku app's stack to `container`:
@@ -31,13 +30,44 @@ You _might_ also need to set your Heroku app's stack to `container`:
 $ heroku stack:set container -a <your-app>
 ```
 
+Configuring your app-config.yaml:
+
+```yaml
+app:
+  # Should be the same as backend.baseUrl when using the `app-backend` plugin
+  baseUrl: https://<your-app>.herokuapp.com
+
+
+backend:
+  baseUrl: https://<your-app>.herokuapp.com
+  listen:
+    port: 
+      $env: PORT 
+      # The $PORT environment variable is a feature of Heroku
+      # https://devcenter.heroku.com/articles/dynos#web-dynos
+```
+
+> Make sure your file is being copied into your container in the Dockerfile.
+
+Before building the Docker image, run the [backstage host build commands](https://backstage.io/docs/deployment/docker#host-build). They must be run whenever you are going to publish a new image.
+
+Heroku runs a container registry on `registry.heroku.com`. To push Backstage
+Docker images, log in to the container registry also:
+
+```shell
+$ heroku container:login
+```
+
 ## Push and deploy a Docker image
 
 Now we can push a Backstage [Docker image](docker.md) to Heroku's container
 registry and release it to the `web` worker:
 
 ```bash
-$ heroku container:push web -a <your-app>
+$ docker image build . -f packages/backend/Dockerfile --tag registry.heroku.com/<your-app>/web
+
+$ docker push registry.heroku.com/<your-app>/web
+
 $ heroku container:release web -a <your-app>
 ```