message: docs: Update custom theme documentation to use extendTheme
  This is an extra commit to comply with commit convention
diff: @@ -101,7 +101,7 @@ const theme = extendTheme({
  },
  })
  -// 3. Consume the text styles in your components
  +// 3. Consume the text styles in your component
  function Example() {
  return <Box textStyle={`h1`}>This is a box</Box>
  }
  