The new 2.1.1 version is not only compatible with Node v8.x but also includes new features to manage plugin versions - such as the ability to check if there are more up-to-date versions of your plugins available.
We're still trying to find the time to update the README, in the meantime you can find out more by looking here or by running
adapt help once you've updated to the latest version.
To update to the latest version, run
npm update -g adapt-cli (with
sudo privileges if your OS requires that)