add some other content in the Advanced section

- prune images and containers
- example of web applications
- special behaviour on Linux if tasks with root are performed in the container (e.g. writing files to shared folders container/host)
- working dir and permissions (`-u "$(id -u):$(id -g)"`)
- MacOS M1 chip specialitites
```
export DOCKER_DEFAULT_PLATFORM=linux/amd64
docker build .
```