This commit updates the cqlsh compatibility
with Python to Python 3.
In addition it:
- Replaces "Cassandra" with "ScyllaDB" in
the description of cqlsh.
The previous description was outdated, as
we no longer can talk about using cqlsh
released with Cassandra.
- Replaces occurrences of "Scylla" with "ScyllaDB".
- Adds additional locations of cqlsh (Docker Hub
and PyPI), as well as the link to the scylla-cqlsh
repository.
Closesscylladb/scylladb#16016