message: improve example with formState
diff: @@ -6,11 +6,13 @@ export default function App() {
  const onSubmit = data => console.log(data);
  // Read the formState before render to subscribe the form state through Proxy
  - const { isDirty, isSubmitting, touched, submitCount } = formState;
  + const { isDirty, isSubmitting } = formState;
  return (
  <form onSubmit={handleSubmit(onSubmit)}>
  <input name="test" ref={register} />
  + {isDirty && <p>Form is dirty.</p>}
  + {isSubmitting && <span>Submitting...</span>}
  <input type="submit" />
  </form>
  );
  