Mailables in 9.x - Build vs Content etc? Is documentation out of sync?

I'm a bit confused why php artisan make:mail OrderShipped creates a file that's different from the documentation which states Once you have generated a mailable class, open it up so we can explore its contents. Mailable class configuration is done in several methods, including the envelope, content, and attachments methods.

Instead, the result is a class that extends Mailable with __construct and build functions, and build is not mentioned in the documentation. I'm just wondering how to customize the mail template as it has the preexisting laravel header/footer and links.