message: docs(icon): improve custom icon wordings
diff: @@ -151,7 +151,7 @@ export const UpDownIcon = createIcon({
  Before generating custom icons do the following:
  -- Export the icon's `svg` from [Figma](https://www.figma.com/),
  +- Export icons as `svg` from [Figma](https://www.figma.com/),
  [Sketch](https://www.sketch.com/), etc.
  - Use a tool like [SvgOmg](https://jakearchibald.github.io/svgomg/) to reduce
  the size and minify the markup.
  