doc upd

Author: michele

README.md

@@ -17,4 +17,4 @@ The official ArangoDB Java Driver.
 - [Examples](src/test/java/com/arangodb/example)
 - [Examples Async](src/test/java/com/arangodb/async/example)
 - [Tutorial](https://www.arangodb.com/tutorials/tutorial-sync-java-driver/)
-- [JavaDoc](http://arangodb.github.io/arangodb-java-driver/javadoc-6_3)
+- [JavaDoc](http://arangodb.github.io/arangodb-java-driver/javadoc-6_4)