Explain why panda_moveit_config is located in ros_planning

README.md

+# Franka Emika Panda MoveIt! Config Package
+
+The Panda robot is the flagship MoveIt! integration robot used in the MoveIt! tutorials.
+Any changes to MoveIt! need to be propagated into this config fast, so this package
+is co-located under the ``ros-planning`` Github organization here.