Add type to express Request import in controllers.md

Hi, 

I'm following the official docs to learn Nest.js, and in the `Controllers` docs the snippet introducing `Request object` didn't compile  in `app.controllers.ts` when doing `npm run start:dev` with the following error:

```
src/app.controller.ts:15:24 - error TS1272: A type referenced in a decorated signature must be imported with 'import type' or a namespace import when 'isolatedModules' and 'emitDecoratorMetadata' are enabled.

15   test(@Req() request: Request): string {
                          ~~~~~~~

  src/app.controller.ts:3:10
    3 import { Request } from 'express';
               ~~~~~~~
    'Request' was imported here.
```

Error was fixed when I added `type` to the import.

Using Node.js v24.8.0 and Nest.js 11.0.10, bootstrapped from the official CLI with `nest new <app>`. (`nest -v` => 11.0.10).

content/controllers.md

@@ -78,7 +78,7 @@ Handlers often need access to the client’s **request** details. Nest provides
 ```typescript
 @@filename(cats.controller)
 import { Controller, Get, Req } from '@nestjs/common';
-import { Request } from 'express';
+import type { Request } from 'express';
 
 @Controller('cats')
 export class CatsController {