Update link to MoveIt! documentation (#846)

(cherry picked from commit 3311cf8)

Co-authored-by: Felix Exner (fexner) <exner@fzi.de>

ur_robot_driver/doc/usage.rst

@@ -189,7 +189,7 @@ To test the driver with the example MoveIt-setup, first start the driver as desc
    ros2 launch ur_moveit_config ur_moveit.launch.py ur_type:=ur5e launch_rviz:=true
 
 Now you should be able to use the MoveIt Plugin in rviz2 to plan and execute trajectories with the
-robot as explained `here <https://moveit.picknik.ai/galactic/doc/tutorials/quickstart_in_rviz/quickstart_in_rviz_tutorial.html>`_.
+robot as explained `here <https://moveit.picknik.ai/main/doc/tutorials/quickstart_in_rviz/quickstart_in_rviz_tutorial.html>`_.
 
 Fake hardware
 ^^^^^^^^^^^^^