docs: fix highlight line (#202)

docs/src/app/docs/nextjs/page.mdx

@@ -101,7 +101,7 @@ export const env = createEnv({
 
 We recommend you importing your newly created file in your `next.config.js`. This will make sure your environment variables are validated at build time which will save you a lot of time and headaches down the road. You can use [unjs/jiti](https://github.com/unjs/jiti) to import TypeScript files in your `next.config.js`:
 
-```js title="next.config.js" {5}
+```js title="next.config.js" {6}
 import { fileURLToPath } from "node:url";
 import createJiti from "jiti";
 const jiti = createJiti(fileURLToPath(import.meta.url));