DOCSP-25436 Added a note about asynchronous Java drivers. (#302)

* DOCSP-25436 Added a note about asynchronous Java drivers.

* DOCSP-25436 Updated note on asynchronous driver based on peer review feedback.

Author: DBirtolo-mdb

source/index.txt

@@ -31,6 +31,10 @@ MongoDB driver for synchronous Java applications. Download it using
 `Gradle <https://gradle.org/>`__, or set up a runnable project by
 following our Quick Start guide.
 
+If your Java application requires asynchronous stream processing, use the
+:driver:`Reactive Streams Driver </reactive-streams/>` which uses Reactive
+Streams to make non-blocking calls to MongoDB.
+
 
 Quick Start
 -----------