docs: use new nuxi module add command in installation

Author: danielroe

README.md

@@ -25,14 +25,7 @@ This module is really just about making it work with Nuxt 3 without the need to
 1. Add `nuxt3-leaflet` dependency to your project
 
 ```bash
-# Using pnpm
-pnpm add -D nuxt3-leaflet
-
-# Using yarn
-yarn add --dev nuxt3-leaflet
-
-# Using npm
-npm install --save-dev nuxt3-leaflet
+npx nuxi@latest module add nuxt3-leaflet
 ```
 
 2. Add `nuxt3-leaflet` to the `modules` section of `nuxt.config.ts`