Specify source files in code examples for useLayoutEffect documentation

Author: armedi

src/content/reference/react/useLayoutEffect.md

@@ -410,7 +410,7 @@ Here is the same example, but with [`useEffect`](/reference/react/useEffect) ins
 
 <Sandpack>
 
-```js
+```js src/App.js
 import ButtonWithTooltip from './ButtonWithTooltip.js';
 
 export default function App() {
@@ -484,7 +484,7 @@ export default function ButtonWithTooltip({ tooltipContent, ...rest }) {
 }
 ```
 
-```js
+```js src/Tooltip.js
 import { useRef, useEffect, useState } from 'react';
 import { createPortal } from 'react-dom';
 import TooltipContainer from './TooltipContainer.js';