message: improve doc on controller/useController and field type
diff: @@ -401,7 +401,7 @@ export default function App() {
  <>
  <p>
  This type is useful when you define custom component's{" "}
  - <code>name</code> prop.
  + <code>name</code> prop, and it will type check again your field path.
  </p>
  <CodeArea
  rawData={`export type FieldPath<TFieldValues extends FieldValues> = Path<TFieldValues>;`}
  