Update Iron.rst

Author: SteveMacenski

migration/Iron.rst

@@ -231,6 +231,11 @@ New Graceful Motion Controller
 
 See :ref:`configuring_graceful_motion_controller` for more information.
 
+Plugin Libraries in BT Navigator Only Includes Custom Nodes
+***********************************************************
+
+New to Jazzy, the ``plugin_lib_names`` parameter implicitly includes all Nav2 BT nodes automatically. It is only required now to specify additional user-generated BT plugins to load.
+
 New RViz Plugin for selecting Planners, Controllers, Goal Checkers, Progress Checkers and Smoothers
 ***************************************************************************************************
 
@@ -248,4 +253,4 @@ In the GIF, it can be seen that there are two controller_ids namely, `FollowPath
 
 In this case, the `FollowPath` is the default controller_id. The difference between the two controller_ids is that HighSpeedFollowPath has a higher max velocity compared to the FollowPath. This difference can be well noted in the GIF.
 
-.. attention:: If a server is unavailable, then the combo box or the drop down list of the particular component will be empty.
+.. attention:: If a server is unavailable, then the combo box or the drop down list of the particular component will be empty.