Add documentation on configuration and usage

README.md

@@ -5,6 +5,36 @@
 This could be done in NodeRed, but it is part of our critical infrastrukture and should
 run independently.
 
+## Usage
+
+### Configuration
+
+Configuration is done using environment variables:
+
+* `PORT`: Target port when used with docker-compose (default `8080`)
+
+### Run with Docker
+
+```bash
+docker run --rm -it \
+    -p 8080:8080 \
+    netz39/ampel-controller
+```
+
+### Run with Docker-Compose (Development)
+
+To run with [docker-compose](https://docs.docker.com/compose/) copy  [`.env.template`](.env.template) to `.env` and edit the necessary variables. Then start with:
+
+```bash
+docker-compose up --build
+```
+
+Please note that this compose file will rebuild the image based on the repository. This is helpful during development and not intended for production use.
+
+When done, please don't forget to remove the deployment with
+```bash
+docker-compose down
+```
 
 ## Maintainers