message: Update select.mdx
  new icon -> new background color
diff: @@ -81,7 +81,7 @@ much any property. Here's we'll override the background color.
  backgroundColor="tomato"
  borderColor="tomato"
  color="white"
  - placeholder="Woohoo! A new icon"
  + placeholder="Woohoo! A new background color!"
  />
  ```
  