Minor clarification

docs/reference/input/light-level.md

@@ -1,6 +1,6 @@
 # Light Level
 
-Find the light level where you are.
+Find the light level (how bright or dark it is) where you are.
 The light level ``0`` means darkness and ``255`` means bright light. 
 The BBC micro:bit measures the light around it by using some of the
 LEDs on the [LED screen](/device/screen).