What:		/sys/class/leds/<led>/device/brightness
Date:		July 2020
KernelVersion:	5.9
Contact:	Marek Behún <marek.behun@nic.cz>
Description:	(RW) On the front panel of the Turris Omnia router there is also
		a button which can be used to control the intensity of all the
		LEDs at once, so that if they are too bright, user can dim them.

		The microcontroller cycles between 8 levels of this global
		brightness (from 100% to 0%), but this setting can have any
		integer value between 0 and 100. It is therefore convenient to be
		able to change this setting from software.

		Format: %i