docs(guide): add nitro plugins to server directory (#7780)

docs/content/2.guide/2.directory-structure/1.server.md

@@ -66,6 +66,21 @@ export default defineEventHandler((event) => {
 })
 ```
 
+## Server Plugins
+
+Nuxt will automatically read any files in the `~/server/plugins` directory and register them as Nitro plugins. This allows extending Nitro's runtime behavior and hooking into lifecycle events.
+
+**Example:**
+
+```ts [server/plugins/nitroPlugin.ts]
+export default defineNitroPlugin((nitroApp) => {
+  console.log('Nitro plugin', nitroApp)
+})
+```
+
+::ReadMore{link="https://nitro.unjs.io/guide/advanced/plugins" title="Nitro Plugins"}
+::
+
 ## Server Utilities
 
 Server routes are powered by [unjs/h3](https://github.com/unjs/h3) which comes with a handy set of helpers.