feat(docs): add description for kit'sinstallModule

docs/3.api/4.advanced/2.kit.md

@@ -14,7 +14,29 @@ description: Nuxt Kit provides composable utilities to help interacting with Nux
 
 [source code](https://github.com/nuxt/nuxt/blob/main/packages/kit/src/module)
 
-- `installModule(module, inlineOptions)`
+#### `installModule(module, inlineOptions)`
+
+Install specified Nuxt module programmatically. This is helpful when your module depends on other modules. You can pass the module options as an object to `inlineOptions` and they will be passed to the module's `setup` function.
+
+```ts
+import { defineNuxtModule, installModule } from '@nuxt/kit'
+
+export default defineNuxtModule<ModuleOptions>({  
+  async setup (options, nuxt) {
+    // will install @nuxtjs/fontaine with Roboto font and Impact fallback
+    await installModule('@nuxtjs/fontaine', {
+      // module configuration
+      fonts: [
+        {
+          family: 'Roboto',
+          fallbacks: ['Impact'],
+          fallbackName: 'fallback-a',
+        }
+      ]
+    })
+  }
+})
+```
 
 ### Programmatic Usage