message: Added example for React Hooks
diff: ### React Hooks
  -A collection of hooks you can use in your React Checkout UI Extension.
  +A collection of [React hooks](https://reactjs.org/docs/hooks-intro.html) are provided to make it easy to update your UI when shopify data has changed.
  +
  +```jsx
  +import React from 'react';
  +import {
  + render,
  + Text,
  + useShippingAddress,
  +} from '@shopify/checkout-ui-extensions-react';
  +
  +render('Checkout::Dynamic::Render', () => <App />);
  +
  +function App() {
  + // Access and subscribe to the shipping address
  + // Your <App /> will automatically re-render when the address has changed
  + const address = useShippingAddress();
  + const firstName = address?.firstName ?? 'guest';
  +
  + // Render UI
  + return <Text>Hi {firstName}!</Text>;
  +}
  +```
  +
  +> Note
  +> React hooks are only available if you are using React. If you are using JavaScript only, you'll need to manually subscribe to the target `StatefulRemoteSubscribable` with a callback. Such as `shippingAddress.subscribe(newValue => updateYourUI())`.
  | Name | Type | Description |
  | ------------------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
  