message: chore: add register usage comment
diff: @@ -15,6 +15,7 @@ function App() {
  <ul>
  {fields.map((item, index) => (
  <li key={item.id}>
  + {/* important: useFieldArray only works with ref={register()} */}
  <input name={\`test[\${index}].name\`} defaultValue={item.name} ref={register()} />
  <button onClick={() => remove(index)}>Delete</button>
  </li>
  