docs: add addComponentsDir example to modules author guide (#24876)

docs/2.guide/3.going-further/3.modules.md

@@ -335,6 +335,22 @@ export default defineNuxtModule({
 })
 ```
 
+Alternatively, you can add an entire directory by using `addComponentsDir`.
+
+```ts
+import { defineNuxtModule, addComponentsDir } from '@nuxt/kit'
+
+export default defineNuxtModule({
+  setup(options, nuxt) {
+    const resolver = createResolver(import.meta.url)
+
+    addComponentsDir({ 
+      path: resolver.resolve('runtime/components') 
+    })
+  }
+})
+```
+
 #### Injecting Composables With `addImports` and `addImportsDir`
 
 If your module should provide composables, you can use the `addImports` utility to add them as auto-imports for Nuxt to resolve.