message: update doc on setError API has no effect on isValid formState
diff: @@ -1250,6 +1250,13 @@ setError('registerInput', { type: 'custom', message: 'custom message' });
  disabled.
  </p>
  </li>
  + <li>
  + <p>
  + This method does not affect <code>isValid</code> formState, as
  + <code>isValid</code> will always be derived by the validation
  + result from your input registration rules or schema result.
  + </p>
  + </li>
  </ul>
  </>
  ),
  