为什么我的 "overtrue/Laravel-lang:~3.0" 安装成功后,报错还是显示英文

vagrant@homestead:~/code/Laravel$ composer require "overtrue/laravel-lang:3.0"
./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)
Package operations: 2 installs, 0 updates, 0 removals
  - Installing caouecs/laravel-lang (3.0.59): Downloading (100%)
  - Installing overtrue/laravel-lang (3.0.0): Downloading (100%)
caouecs/laravel-lang suggests installing arcanedev/laravel-lang (Translations ma         nager and checker for Laravel 5)
caouecs/laravel-lang suggests installing ablunier/laravel-lang-installer (Comman         d for easily add languages to a Laravel project)
caouecs/laravel-lang suggests installing andrey-helldar/laravel-lang-publisher (         Easy installation and update of translation files for your project)
Writing lock file
Generating optimized autoload files
> Illuminate\Foundation\ComposerScripts::postAutoloadDump
> @php artisan package:discover
Discovered Package: fideloper/proxy
Discovered Package: laravel/tinker
Discovered Package: nesbot/carbon
Package manifest generated successfully.
vagrant@homestead:~/code/Laravel$

config/app.php 里面添加Overtrue\LaravelLang\TranslationServiceProvider::class, 才显示,不是说自动注册的嘛,我的laravel版本5.5