Update reading-files-with-nodejs.md (nodejs#6684)

change lang from "js" to "cjs" for consistency

Signed-off-by: huseeiin <122984423+huseeiin@users.noreply.github.com>

pages/en/learn/manipulating-files/reading-files-with-nodejs.md

@@ -58,7 +58,7 @@ try {
 
 You can also use the promise-based `fsPromises.readFile()` method offered by the `fs/promises` module:
 
-```js
+```cjs
 const fs = require('node:fs/promises');
 
 async function example() {