docs(env): mention vite/client.d.ts (vitejs#5457)

docs/guide/env-and-mode.md

@@ -53,13 +53,15 @@ If you want to customize env variables prefix, see [envPrefix](/config/index#env
 - Since any variables exposed to your Vite source code will end up in your client bundle, `VITE_*` variables should _not_ contain any sensitive information.
   :::
 
-### IntelliSense
+### IntelliSense for TypeScript
 
-By default, Vite provides type definition for `import.meta.env`. While you can define more custom env variables in `.env.[mode]` files, you may want to get TypeScript IntelliSense for user-defined env variables which prefixed with `VITE_`.
+By default, Vite provides type definition for `import.meta.env` in [`vite/client.d.ts`](https://github.com/vitejs/vite/blob/main/packages/vite/client.d.ts). While you can define more custom env variables in `.env.[mode]` files, you may want to get TypeScript IntelliSense for user-defined env variables which prefixed with `VITE_`.
 
 To achieve, you can create an `env.d.ts` in `src` directory, then augment `ImportMetaEnv` like this:
 
 ```typescript
+/// <reference types="vite/client" />
+
 interface ImportMetaEnv extends Readonly<Record<string, string>> {
   readonly VITE_APP_TITLE: string
   // more env variables...