i2c-dev should also be added to the loaded modules

Changing only the boot configuration to load the i2c-gpio overlay is not
sufficient, the i2c-dev module should also be loaded.
raspi-config does this when enabling the i2c interface.

INSTALL.md

@@ -55,6 +55,9 @@ Ensure that the line `dtparam=i2c_arm=on` is not present: that would
 activate the hardware I²C bus, which cannot be used due to a hardware
 bug in the BCM2712 SOC with regard to clock stretching.
 
+Ensure that `i2c-dev` is also present in `/etc/modules` (should be
+the case if you have used `raspi-config` to enable the I²C interface).
+
 The Python module is located in `controller/python/controller.py`.
 
 ### Firmware updater

[Tarik Graba]

@sam /etc/modules ou je cherche comment le charger avec la cmdline?

[Samuel Tardieu]

@tarik Comme tu veux, ça peut avoir aussi un but didactique de leur faire configurer