More modularity and reworked readme

- Docker's init added to avoid zombie processes (i.e. Unbound)
- Added environment variables to enable or disable features: `DOT`, `FIREWALL`
- Reworked readme

docker-compose.yml

@@ -9,6 +9,7 @@ services:
     devices:
       - /dev/net/tun
     network_mode: bridge
+    init: true
     environment:
       - USER=js89ds7
       - PASSWORD=8fd9s239G