This PR removes the incorrect information that the ScyllaDB Rust Driver is not GA.
In addition, it replaces "Scylla" with "ScyllaDB".
Fixes https://github.com/scylladb/scylladb/issues/16178
Closes scylladb/scylladb#16199
* github.com:scylladb/scylladb:
doc: remove the "preview" label from Rust driver
doc: fix Rust Driver release information
(cherry picked from commit 56c3515751)