update license

README.md

@@ -1,5 +1,5 @@
 ---
-license: mit
+license: cc-by-nc-sa-4.0
 task_categories:
 - visual-question-answering
 - text-generation
@@ -85,4 +85,17 @@ If you find our dataset useful, please consider citing
   year={2023}
 }
 
-```
+```
+
+License
+===================================================================================================
+[![CC BY-NC-SA 4.0][cc-by-nc-sa-shield]][cc-by-nc-sa]
+
+Being aligned with original nuScenes' license, this work is licensed under a
+[Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License][cc-by-nc-sa].
+
+[![CC BY-NC-SA 4.0][cc-by-nc-sa-image]][cc-by-nc-sa]
+
+[cc-by-nc-sa]: http://creativecommons.org/licenses/by-nc-sa/4.0/
+[cc-by-nc-sa-image]: https://licensebuttons.net/l/by-nc-sa/4.0/88x31.png
+[cc-by-nc-sa-shield]: https://img.shields.io/badge/License-CC%20BY--NC--SA%204.0-lightgrey.svg