fix: updated correct line highlight in auto-embed docs page

docs/src/content/docs/integration.mdx

@@ -9,7 +9,7 @@ The Astro Embed integration automatically converts URLs in MDX files to embed co
 
 To enable the integration, add it to the `integrations` array in your `astro.config.mjs` file before the `mdx()` integration:
 
-```js ins={3} ins="embeds()"
+```js ins={4} ins="embeds()"
 // astro.config.mjs
 import { defineConfig } from 'astro/config';
 import mdx from '@astrojs/mdx';