update release notes

doc/release_notes.rst

@@ -105,6 +105,10 @@ hardware_interface
 * Added ``get_hardware_info`` method to the hardware components interface to access the ``HardwareInfo`` instead of accessing the variable ``info_`` directly (`#1643 <https://github.com/ros-controls/ros2_control/pull/1643>`_)
 * With (`#1683 <https://github.com/ros-controls/ros2_control/pull/1683>`_) the ``rclcpp_lifecycle::State & get_state()`` and ``void set_state(const rclcpp_lifecycle::State & new_state)`` are replaced by ``rclcpp_lifecycle::State & get_lifecycle_state()`` and ``void set_lifecycle_state(const rclcpp_lifecycle::State & new_state)``. This change affects controllers and hardware. This is related to (`#1240 <https://github.com/ros-controls/ros2_control/pull/1240>`_) as variant support introduces ``get_state`` and ``set_state`` methods for setting/getting state of handles.
 
+InterfaceInfo
+*************
+* With (`#1421 <https://github.com/ros-controls/ros2_control/pull/1421>`_) a key-value storage is added to InterfaceInfo. This allows to define extra params with per Command-/StateInterface in the ``.ros2_control.xacro`` file.
+
 joint_limits
 ************
 * Add header to import limits from standard URDF definition (`#1298 <https://github.com/ros-controls/ros2_control/pull/1298>`_)