Add "Cleanup" section

The list of operations :
```bash
$ cat ~/.bin/docker-cleanup.sh
#!/bin/bash

docker stop $(docker ps -q) ;
docker rm $(docker ps -aq)

echo
docker network ls
docker network prune -f
docker builder prune -f
```
@tcompa

Start by inspecting the TUI's existing operation sections and the Docker command handling. Use the listed cleanup commands as the required operations; done means a Cleanup section exposes these operations consistently with the other sections.

Written by the indexing model from the issue text.