docs: use new nuxi module add command in installation (#1606)

Co-authored-by: Benjamin Canac <canacb1@gmail.com>

docs/content/1.getting-started/2.installation.md

@@ -5,29 +5,13 @@ description: 'Learn how to install and configure Nuxt UI in your application.'
 
 ## Setup
 
-1. Install `@nuxt/ui` dependency to your project:
+1. Add `@nuxt/ui` module to your project:
 
-::code-group
-
-```bash [pnpm]
-pnpm add @nuxt/ui
+```bash
+npx nuxi@latest module add ui
 ```
 
-```bash [yarn]
-yarn add @nuxt/ui
-```
-
-```bash [npm]
-npm install @nuxt/ui
-```
-
-```bash [bun]
-bun add @nuxt/ui
-```
-
-::
-
-2. Add it to your `modules` section in your `nuxt.config`:
+2. Add it to the `modules` section in your `nuxt.config.ts`:
 
 ```ts [nuxt.config.ts]
 export default defineNuxtConfig({