docs(example): update README

Replaces `npm` → `pnpm`.

Author: kikuomax

example/README.md

@@ -33,13 +33,13 @@ Please replace `<Your Mapbox Access Token Here>` with your Mapbox access token.
 ### Resolving dependencies
 
 ```sh
-npm install
+pnpm install --frozen-lockfile
 ```
 
 ### Running the example on a dev server
 
 ```sh
-npm run dev
+pnpm dev
 ```
 
 A dev server will be hosted on http://localhost:5173.

example/README_ja.md

@@ -33,13 +33,13 @@ export const MAPBOX_ACCESS_TOKEN = '<Your Mapbox Access Token Here>';
 ### 依存関係を解決する
 
 ```sh
-npm install
+pnpm install --frozen-lockfile
 ```
 
 ### 開発サーバーでサンプルを動かす
 
 ```sh
-npm run dev
+pnpm dev
 ```
 
 開発サーバーは http://localhost:5173 でホストされます。