This PR is a follow-up to https://github.com/scylladb/scylladb/pull/15742#issuecomment-1766888218.
It adds CQL Reference for Materialized Views to the Materialized Views page.
In addition, it removes the irrelevant information about when the feature was added and replaces "Scylla" with "ScyllaDB".
(nobackport)
Closesscylladb/scylladb#15855
* github.com:scylladb/scylladb:
doc: remove versions from Materialized Views
doc: add CQL Reference for Materialized Views