README: add mirror provenance notice

README.md

@@ -3997,6 +3997,14 @@ configs:
     - data/chunk-003/file-943.parquet
     - data/chunk-003/file-944.parquet
 ---
+
+<!-- OpenWAM mirror -->
+> **Mirror notice**: this is a repack of
+> [VLABench/vlabench_primitive_ft_lerobot_video](https://huggingface.co/datasets/VLABench/vlabench_primitive_ft_lerobot_video)
+> into large tar archives for fast transfer (content unchanged; all credit to the
+> original VLABench authors). Download and unpack via OpenWAM's
+> scripts/download_assets/download_benchmark_data.py.
+
 # VLABench Primitive Tasks Dataset - LeRobot v3.0
 
 ## Dataset Description