Docs: document available releases and matching upstream releases

[tzach]

Datastax - 3.21.0 3.22.0 3.23.0 3.24.0
https://pypi.org/project/cassandra-driver/#history

Our Release versions - 3.21.0 3.22.0 3.22.1 3.22.2 3.22.3 3.24.0 3.24.1
https://pypi.org/project/scylla-driver/#history

[tzach]

@fruch the info is from you