Fixed typo in reference docs

Thanks to https://github.com/arogulin for spotting it.

Author: jyemin

docs/reference/content/driver-async/index.md

@@ -16,7 +16,7 @@ The callback-based Async Java Driver has been deprecated in favor of the
 [MongoDB Reactive Streams Java Driver](http://mongodb.github.io/mongo-java-driver-reactivestreams/).
 {{% /note %}}
 
-### What's New in 3.19
+### What's New in 3.10
 
 The driver now natively supports TLS/SSL when used with Java 8+.