add docs to loadCacheRoutes in RouteServiceProvider

[ahmedabdel3al]

laravel/framework#51292 After Laravel added loadCachedRoutesUsing method to RouteServiceProvider

we can use it to fix the problem of loading cached routes in Laravel 11

in AppServiceProvider use put the following in register method

class AppServiceProvider extends ServiceProvider
{  
    use \Mcamara\LaravelLocalization\Traits\LoadsTranslatedCachedRoutes;
    /**
     * Bootstrap any application services.
     */
    public function boot(): void
    {
        RouteServiceProvider::loadCachedRoutesUsing(fn() => $this->loadCachedRoutes());
        ...
    }  

[kminek]

@mcamara can we merge this? this is very important for L11 users as there is no RouteServiceProvider anymore in L11 skeleton and the docs are confusing regarding route caching.

[mcamara]

thanks for your commit, I'll merge it!