leds: Adjust documentation of brightness sysfs node

Adjust documentation of brightness sysfs node about accepted value range.
The code accepts only decimal values. We may not relax that due to different
readings for, e.g., octal 0100, which becomes 64 instead of currently parsed
100.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/20260513220620.369825-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Lee Jones <lee@kernel.org>

Author: andy-shev

Documentation/ABI/testing/sysfs-class-led

@@ -22,8 +22,8 @@ Description:
 		  For additional details please refer to
 		  Documentation/leds/leds-class-multicolor.rst.
 
-		The value is between 0 and
-		/sys/class/leds/<led>/max_brightness.
+		The value is between 0 and /sys/class/leds/<led>/max_brightness
+		and is represented by as a decimal.
 
 		Writing 0 to this file clears active trigger.