docs: update DEVELOPING.md

DEVELOPING.md

@@ -6,14 +6,19 @@ Thanks a lot for contributing to Komga!
 
 You will need:
 
-- Java JDK version 8 or 11
-- Nodejs version 10+, with `npm` version 6+
+- Java JDK version 8+
+- Nodejs version 16+
+
+## Setting up the project
+
+- run `npm install` in the root folder of the project. This will install the necessary commit hooks.
+- run `npm install in the `komga-webui` folder of the project. This will install the necessary tooling for the webui.
 
 ## Commit messages
 
 Komga's commit messages follow the [Conventional Commits](https://www.conventionalcommits.org/) standard. This enables automatic versioning, releases, and release notes generation.
 
-Commit messages are enforced using commit hooks ran on the developer's PC. To install the necessary tooling, you need to run `npm install` in the root folder of the project. This will install the necessary commit hooks.
+Commit messages are enforced using commit hooks ran on the developer's PC.
 
 ## Project organization
 
@@ -61,3 +66,11 @@ SET SPRING_PROFILES_ACTIVE=dev
 You can run a live development server with `npm run serve` from `/komga-webui`. The dev server will override the URL to connect to `localhost:8080`, so you can also run `gradle bootRun` to have a backend running, serving the API requests. The frontend will be loaded from `localhost:8081`.
 
 Make sure you start the backend with the `dev` profile, else the frontend requests will be denied because of CORS.
+
+## Docker
+
+To build the Docker image, you need to:
+- have the webui built and copied to `/resources/public`. To do so, run `./gradlew copyWebDist`
+- unpack the jar into layers expected by the `Dockerfile`. To do so, run `./gradlew unpack`
+
+Then you can run `docker build -f ./komga/Dockerfile .`