message: fix: update usecontrasttext example to fix docs
diff: import React from 'react';
  import { Button, Center, VStack, useContrastText } from 'native-base';
  export const Example = () => {
  - const bgDark = 'gray.900';
  - const bgLight = 'gray.50';
  + const bgDark = 'coolGray.900';
  + const bgLight = 'coolGray.100';
  const colorContrastDark = useContrastText(bgDark);
  const colorContrastLight = useContrastText(bgLight);
  return (
  