Since 2017-06-17, Magento 2.2 includes a new «Robots» module

https://github.com/magento/magento2/commit/33e65e0b

https://github.com/magento/magento2/blob/33e65e0b/composer.json#L160-L160

https://github.com/magento/magento2/blob/33e65e0b/app/code/Magento/Robots/README.md

See also: