Please update documentation

[liouma]

The installation procedure is as follow:

• Installer l'image 1.0.2
• créer un fichier vide ssh à la racine de la carte
• installer la carte dans le pi puis :
• se loguer en ssh:
• cd /opt/pynab
• source /opt/pynab/venv/bin/activate
• pip install paho-mqtt==1.6.1
• git clone https://github.com/nopap/nab2mqttd
• cd /opt/pynab/nab2mqttd
• sudo cp nab2mqttd.service /lib/systemd/system/
• cd ..
• Edit nabweb/settings.py and add "nab2mqttd" in the INSTALLED_APPS section
• Generate migrations files : python manage.py makemigrations
• Apply migration : python manage.py migrate
• Reload systemd unit definition : sudo systemctl daemon-reload
• Enable service (start on rabbit boot): sudo systemctl enable nab2mqttd
• Start service: sudo systemctl start nab2mqttd
• Make sure the service is working fine (check logs): sudo journalctl -u nab2mqttd
• Restart nabweb: sudo service nabweb restart