[7.x] Fix doc stub console command

[sunh-2087]

In Document Laravel 7.x function handle() return integer.

Symfony Console, which is the underlying component that powers Artisan, expects all commands to return an integer. Therefore, you should ensure that any of your commands which return a value are returning integer

public function handle()
{
    // Before...
    return true;

    // After...
    return 0;
}

[driesvints]

Thanks