add docs (#339)

Author: Tony Najjar

migration/Humble.rst

@@ -8,3 +8,7 @@ Moving from ROS 2 Humble to Iron, a number of stability improvements were added
 Added Collision Monitor
 ***********************
 `PR 2982 <https://github.com/ros-planning/navigation2/pull/2982>`_ adds new safety layer operating independently of Nav2 stack which ensures the robot to control the collisions with near obstacles, obtained from different sensors (LaserScan, PointCloud, IR, Sonars, etc...). See :ref:`configuring_collision_monitor` for more details. It is not included in the default bringup batteries included from ``nav2_bringup``.
+
+Removed use_sim_time from yaml
+******************************
+`PR #3131 <https://github.com/ros-planning/navigation2/pull/3131>`_ makes it possible to set the use_sim_time parameter from the launch file for multiple nodes instead of individually via the yaml files. If using the Nav2 launch files, you can optionally remove the use_sim_time parameter from your yaml files and set it via a launch argument.