Document data format change

data_generation/blenderproc_data_gen/README.md

@@ -31,3 +31,11 @@ at the source-code itself; `blenderproc run ./generate_training_data.py --help`
 them properly.
 
 Blenderproc searches for python modules in a different order than when invoking Python by itself.  If you run into an issue where `generate_training_data.py` fails to import modules that you have installed, you may have to re-install them via blenderproc; e.g. `blenderproc pip install pyquaternion`.
+
+## Versioning Notes
+
+10 June 2024
+
+The order of the `projected_cuboid` points generated by the Blenderproc scripts changed with
+changelist `22a2468`.  This fix rotated the points 180 degrees around the Z (vertical axis). Do not
+intermingle data generated before this change with data generated after it.