Upgrade guides are available for:
Upgrade Scylla from 1.7.x to 2.0.y on Red Hat Enterprise Linux and CentOS
Upgrade Scylla from 1.7.x to 2.0.y on Ubuntu
Upgrade Scylla from 1.7.x to 2.0.y on Debian
Scylla Metrics Update - Scylla 1.7 to 2.0