Readme: update.

README.md

@@ -1,2 +1,19 @@
 # moveit_mpp
-Multi-planner plugin hoster plugin for MoveIt
+
+## Overview
+
+A proof-of-concept *multi planner plugin planner plugin* for MoveIt.
+
+## State
+
+This is demo code at best. Use at your own risk. It will crash, it may do strange things.
+
+It was just an experiment to see whether this approach could/would be a viable way of getting MoveIt to work with multiple planning plugins without extensive changes to the rest of its infrastructure.
+
+## Known issues
+
+While this can successfully load multiple MoveIt planning plugins, the rest of MoveIt does not know about this (or care). One example are the planning adapters: those are active for all planners (as those are configured per `move_group`) while that may not be needed or desirable.
+
+## Roadmap
+
+No further development of this code is currently planned. It is also not used in any systems that the author maintains.