[5.8] Documenting --parent artisan make:controller option

[itainathaniel]

Two years ago laravel/framework#18606 was merged to the framework without a documentation.

[ahinkle]

You can use php artisan help make:controller to see the full command documentation and options.

[itainathaniel]

@ahinkle I know.
But the fact that something is explained on the help of the command doesn't exclude it from being on the official Laravel documentation

[taylorotwell]

Capitalization and grammar does not match rest of the framework.