Dockerfile: add volume for usernetes configuration

[offlinehacker]

Sometimes it is desirable to mount a volume for usernetes configuration, one use case is that other container can mount same volume and have access to kubeconfig. This change adds volume to /home/user/.config/usernetes.

[offlinehacker]

This is example usage with docker-compose, I am using this with vscode remote containers

version: '3'
services:
  dev:
    ...
    environment:
      KUBECONFIG: /usernetes/master/admin-localhost.kubeconfig
    volumes:
      - usernetes-config:/usernetes
    network_mode: "service:usernetes"

  usernetes:
    image: ghcr.io/xtruder/usernetes:latest
    tty: true
    privileged: true
    command: --cri=containerd
    volumes:
      - usernetes-config:/home/user/.config
      - usernetes-data:/home/user/.local
    hostname: "usernetes"
    network_mode: "bridge"

volumes:
  usernetes-config:
  usernetes-data: