Added "and/or brightness (e.g. monochromatic)" to the Random Effect d…

…escription (#4061)

The Random Effect can also affect the brightness instead of color (e.g. monochromatic light components). I'm not sure if the brightness is also affected for RGB light components, so I put it as an "and/or" instead of just an "or." Of course, adjust based on how it actually works with RGB lights.

components/light/index.rst

@@ -526,7 +526,7 @@ Configuration variables:
 Random Effect
 *************
 
-This effect makes a transition (of length ``transition_length``) to a randomly-chosen color every ``update_interval``.
+This effect makes a transition (of length ``transition_length``) to a randomly-chosen color and/or brightness (e.g. monochromatic) every ``update_interval``.
 
 .. code-block:: yaml