feat(palette): update docs

guides/COLORS.stories.mdx

@@ -8,10 +8,10 @@ import { Meta, Preview } from '@storybook/addon-docs/blocks';
 
 All the colors in palette are created with the same principle.
 
-Each colour includes seven shades, the base colour (color400) and six shades deriving from color400,
+Each color includes seven shades, the base color (color400) and six shades deriving from color400,
 three darker and three lighter.
 
-All new shades are calculated with colour percentages (25%, 50%, 75%) on white background for the lighter shades and black background for the darker ones (75%, 50%, 25%).
+All new shades are calculated with color percentages (25%, 50%, 75%) on white background for the lighter shades and black background for the darker ones (75%, 50%, 25%).
 
 For example magenta `#d21e75`, and we take 3 darker shades and 3 lighter shades, all with a 25% step.
 
@@ -28,7 +28,3 @@ This way we get the following colors for magenta
   700: "#34071d"
 }
 ```
-
-lightGray and darkGray palettes are excluded from the above rule.
-
-The grays start from the darkest one, which is #010101 and get lighter with 8% percentage on each step, except the last one that's pure white.