wallpapers: rephrase color-aware wallpaper option to be accurate
In the past it reflected the lightness or darkness of the color scheme, but this was changed in d678ab7f to reflect the Plasma style. Update the text to match the implementation.
In the past it reflected the lightness or darkness of the color scheme, but this was changed in d678ab7f to reflect the Plasma style. Update the text to match the implementation.