Add EventsExecutor release notes

source/Releases/Release-Iron-Irwini.rst

@@ -232,6 +232,29 @@ To make this a bit better, there is now a new ``NodeInterfaces`` class that can
 
 There are examples on how to use this in https://github.com/ros2/rclcpp/pull/2041.
 
+Introduction of a new executor type: the Events Executor
+""""""""""""""""""""""""""""""""""""""""""""""""""""""""
+
+The ``EventsExecutor`` from iRobot has been merged into the main ``rclcpp`` codebase.
+This alternative executor implementation uses event-driven callbacks from the middleware implementations to fire callbacks at the ``rclcpp`` layer.
+In addition to the push-based model, the `EventsExecutor` also moves timer management into a separate thread, which can allow for more accurate results and lower overhead, especially with many timers.
+
+The ``EventsExecutor`` has a substantial set of documentation and use-in-practice that make a strong candidate for inclusion the the ``rclcpp`` codebase.
+For information about the initial implementation proposal as well as performance benchmarks, see https://discourse.ros.org/t/ros2-middleware-change-proposal/15863.
+For more information about the design, see the design PR: https://github.com/ros2/design/pull/305.
+
+Since the API is the same, trying the ``EventsExecutor`` is as straighforward as replacing your current Execotr implmentation (eg. ``SingleThreadedExecutor``):
+
+.. code-block:: C++
+
+ #include <rclcpp/experimental/executors/events_executor/events_executor.hpp>
+ using rclcpp::experimental::executors::EventsExecutor;
+
+ EventsExecutor executor;
+ executor.add_node(node);
+ executor.spin();
+
+
 ``rclpy``
 ^^^^^^^^^