feat: doc for app controller

back/src/app.controller.ts

@@ -1,11 +1,13 @@
 import { Controller, Get } from '@nestjs/common';
 import { AppService } from './app.service';
+import { ApiOkResponse } from '@nestjs/swagger';
 
 @Controller()
 export class AppController {
 	constructor(private readonly appService: AppService) {}
 
 	@Get()
+	@ApiOkResponse({ description: 'Return a hello world message, used as a health route' })
 	getHello(): string {
 		return this.appService.getHello();
 	}