Add migration notes for jazzy

Author: Felix Exner

doc/migration/jazzy.rst

@@ -0,0 +1,22 @@
+ur_description
+^^^^^^^^^^^^^^
+
+ros2_control xacro tag moved to driver package
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The description package no longer adds the ``ros2_control`` tag to the robot's URDF. This is done
+in the driver / simulation repos now. The description package still provides macros for the
+system-independent parts such as joint configurations and an example using mock_hardware with the
+robot.
+
+Enforce absolute paths in launchfiles
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The ``view_ur.launch.py`` launchfile now expects an absolute path for the description file and RViz
+config file. Before it was expecting a ``description_package`` and a ``description_file`` argument
+with a relative path to the package.
+This way, users can provide their own description file and / or RViz config without the need to
+replicate the complete package structure.
+
+Absolute paths can still be generated dynamically using a package + relative path structure inside
+other launchfiles or by using ``ros2 pkg prefix`` on the command line.