Fix node version for dev container and add it to the readme

* Align node versions to 14 as the build no longer works with node 12
* Add dev container to readme

.devcontainer/Dockerfile

@@ -1,7 +1,7 @@
 # See here for image contents: https://github.com/microsoft/vscode-dev-containers/tree/v0.191.1/containers/javascript-node/.devcontainer/base.Dockerfile
 
-# [Choice] Node.js version: 16, 14, 12
-ARG VARIANT="16-buster"
+# [Choice] Node.js version: 16, 14
+ARG VARIANT="14"
 FROM mcr.microsoft.com/vscode/devcontainers/javascript-node:0-${VARIANT}
 
 # [Optional] Uncomment this section to install additional OS packages.

.devcontainer/devcontainer.json

@@ -4,9 +4,9 @@
 	"name": "Node.js",
 	"build": {
 		"dockerfile": "Dockerfile",
-		// Update 'VARIANT' to pick a Node version: 12, 14, 16
+		// Update 'VARIANT' to pick a Node version: 14, 16
 		"args": {
-			"VARIANT": "12"
+			"VARIANT": "14"
 		}
 	},
 	// Set *default* container specific settings.json values on container create.

README.md

@@ -37,6 +37,14 @@ In addition, EclipseSource also offers [professional support](https://jsonforms.
 * Install dependencies: `npm ci`
 * Hook up dependencies between packages: `npm run init`
 
+### VS Code dev container
+
+As an alternative to the first time setup, you can use the provided [VS Code dev container](https://code.visualstudio.com/docs/remote/containers) configured in [devcontainer.json](.devcontainer/devcontainer.json).
+
+* Execute command: `Remote Containers: Reopen in container`
+* Wait until the container is built and loaded
+* First time setup and an initial build of all packages has been executed in the container
+
 ### Build & Testing
 
 * Build (all packages): `npm run build`