Add example of systemd installation to README.md

[Areso]

Systemd editing

Create file /etc/systemd/system/my_script.service with following contents:

[Unit]
Description=My script that requires network
After=network.target

[Service]
Type=oneshot
ExecStart=/full/path/to/my_script.sh

[Install]
WantedBy=multi-user.target

Then execute:

sudo systemctl daemon-reload
sudo systemctl enable my_script

[Areso]

Also, may be used:
supervisord, rc.local, s6.overlay