Fix build on x86_64 systems (see https://github.com/RPi-Distro/pi-gen/issues/316)

Dockerfile

-FROM debian:buster
+FROM i386/debian:buster
 
 ENV DEBIAN_FRONTEND noninteractive
 

config.example

 # Automatically connect to a wifi network on first boot
-WPA_ESSID=my_ssid
-WPA_PASSWORD=my_password
+WPA_ESSID='my_ssid'
+WPA_PASSWORD='my_password'
 WPA_COUNTRY=FR
 
-# Machine name
+# Hostname
 IMG_NAME=thymio-raspbian
 TARGET_HOSTNAME=thymio-raspbian