Update build-css-js.md

Author: rowanparker

docs/build-css-js.md

@@ -3,9 +3,6 @@
 This example uses `npm` and [Webpack Encore](https://symfony.com/doc/current/frontend.html).
 
 Modify `Dockerfile` to build your assets before anything else.
-The output in `public/build` (the configuration default) will then be copied to both caddy and php.
-
-In your production environment, this is all you need for an immutable release.
 
 ```diff
 ARG CADDY_VERSION=2
@@ -23,6 +20,8 @@ ARG CADDY_VERSION=2
 # "php" stage
 ```
 
+Then copy the built output in `public/build` (the configuration default) to the `php` container (which will then be copied later to `caddy`).
+
 ```diff
 VOLUME /srv/app/var
 
@@ -34,7 +33,8 @@ CMD ["php-fpm"]
 FROM caddy:${CADDY_VERSION}-builder-alpine AS symfony_caddy_builder
 ```
 
-Modify `docker-compose.override.yml` to add an `npm` container in your development environment and watch for file changes.
+Modify `docker-compose.override.yml` to add a `node` container in your development environment.
+This will provide you with hot module reloading.
 
 ```diff
   caddy:
@@ -54,3 +54,6 @@ Modify `docker-compose.override.yml` to add an `npm` container in your developme
 +       protocol: tcp
 +    command: 'sh -c "npm install; npm run dev-server -- --client-web-socket-url https://localhost:8080 --host 0.0.0.0"'
 ```
+
+If file changes are not picked up, refer to this page:
+https://symfony.com/doc/current/frontend/encore/virtual-machine.html#file-watching-issues