Docs: make them more Scylla-specific

[avelanarius]

Many docs pages, such as:

https://java-driver.docs.scylladb.com/stable/manual/compression/index.html https://java-driver.docs.scylladb.com/stable/manual/load_balancing/index.html

start by "Cassandra’s binary protocol ...", "A Cassandra cluster is ...", as they are unmodified from the upstream.

The doc pages should mention that this information is also relevant to Scylla and mention Scylla's best practices (as it relates to load balancing etc.).