Document Datastax driver version support.

Closes #1096.

Author: mp911de

README.adoc

@@ -20,7 +20,7 @@ With the power to stay at a high level with annotated POJOs, or at a low level w
 * Exception Translation to the familiar Spring DataAccessException hierarchy
 * Convenient QueryBuilders to eliminate the need to learn CQL
 * Automatic implementation of Repository interfaces including support for custom query methods
-* Based on the 3.x DataStax CQL Java Driver
+* Based on the 4.x DataStax CQL Java Driver
 
 == Code of Conduct
 

src/main/asciidoc/preface.adoc

@@ -61,7 +61,7 @@ https://docs.datastax.com/en/landing_page/doc/landing_page/current.html[DataStax
 
 Spring Data for Apache Cassandra 2.x binaries require JDK level 8.0 and later and https://spring.io/docs[Spring Framework] {springVersion} and later.
 
-It requires https://cassandra.apache.org/[Cassandra] 2.0 or later.
+It requires https://cassandra.apache.org/[Cassandra] 2.0 or later and Datastax driver 4.x.
 
 == Additional Help Resources