Bump version to v2.3.0 and update Readme

Change-Id: I24fb3042e99c70b38991ac1bee5df0e5c411d2f2
diff --git a/pom.xml b/pom.xml
index c02b962..9953fed 100644
--- a/pom.xml
+++ b/pom.xml
@@ -6,7 +6,7 @@
 
     <groupId>groupId</groupId>
     <artifactId>totalngrams</artifactId>
-    <version>2.2.3</version>
+    <version>2.3.0</version>
 
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>