changed 4.0+ to 4.0.x

Author: emeliawilkinson24

README.md

@@ -36,7 +36,7 @@ This driver is based on [the cql-rb gem](https://github.com/iconara/cql-rb) by [
 
 This driver works exclusively with the Cassandra Query Language v3 (CQL3) and Cassandra's native protocol. The current version works with:
 
-* Apache Cassandra versions 2.1, 2.2, 3.0+, and 4.0+
+* Apache Cassandra versions 2.1, 2.2, 3.0+, and 4.0.x
 * DataStax Enterprise 4.8 and above. However, the [Ruby DSE driver](https://docs.datastax.com/en/developer/ruby-driver-dse/2.1/) provides more features and is recommended for use with DataStax Enterprise.
 * Ruby (MRI) 2.2, 2.3, 2.4
 * JRuby 9k