Add frontend image example

Author: valentinab25

docs/install/containers/images/frontend.md

@@ -33,6 +33,75 @@ This image is **not a base image** to be extended in your projects, but an examp
 For an extensive list of environment variables used by the frontend, visit {doc}`/volto/configuration/environmentvariables`.
 ```
 
+## As an example for your volto project
+
+To use this image as an example of a docker image for your own volto project, you will need to copy the [`Dockerfile`](https://github.com/plone/plone-frontend/blob/main/Dockerfile) file in your project.
+
+In the `Dockerfile` file, replace the `yo @plone/volto` command with the `COPY . /build/plone-frontend` command.
+
+### Create a custom entrypoint
+
+The `plone-frontend` docker image does not have a custom entrypoint file, so for any commands you need to run on docker container start, you will need to create it.
+
+After creating the `entrypoint.sh` file, make sure it has execute permission by running `chmod 755 entrypoint.sh`.
+
+```{note}
+Do not forget to add the `exec "$@"` command at the end of the `entrypoint.sh` file, to run the default `yarn start` command.
+```
+
+In the `Dockerfile` you will need to add this 2 commands to make the docker container run it on start:
+
+```Dockerfile
+COPY entrypoint.sh /
+ENTRYPOINT ["/entrypoint.sh"]
+```
+
+### Build
+
+Build your new image.
+
+```shell
+docker build . -t myfrontend:latest -f Dockerfile
+```
+
+### Start it
+
+You can use it in this `docker-compose.yml` file 
+
+```yaml
+version: "3"
+services:
+
+  backend:
+    image: plone/plone-backend:6.0.0a4
+    # Plone 5.2 series can be used too
+    # image: plone/plone-backend:5.2.7
+    ports:
+      - '8080:8080'
+    environment:
+      - SITE=Plone
+      - 'ADDONS=plone.restapi==8.21.0 plone.volto==4.0.0a3 plone.rest==2.0.0a2 plone.app.iterate==4.0.2 plone.app.vocabularies==4.3.0'
+      - 'PROFILES=plone.volto:default-homepage'
+
+  frontend:
+    image: 'myfrontend:latest'
+    ports:
+      - '3000:3000'
+    restart: always
+    environment:
+      # These are needed in a Docker environment since the
+      # routing needs to be amended. You can point to the
+      # internal network alias.
+      RAZZLE_INTERNAL_API_PATH: http://backend:8080/Plone
+      RAZZLE_DEV_PROXY_API_PATH: http://backend:8080/Plone
+    depends_on:
+      - backend
+```
+
+To start, run
+```shell
+docker-compose up -d
+```     
 
 ## Versions