Fix license information in qasc dataset card (#4951)

Fix license in qasc dataset card

Commit from https://github.com/huggingface/datasets/commit/0249cd8f94bb5fed13954dd5bb5ab6ea29dbcbf0

README.md

@@ -6,7 +6,7 @@ language:
 language_creators:
 - found
 license:
-- unknown
+- cc-by-4.0
 multilinguality:
 - monolingual
 pretty_name: Question Answering via Sentence Composition (QASC)
@@ -173,7 +173,7 @@ The data fields are the same among all splits.
 
 ### Licensing Information
 
-[More Information Needed](https://github.com/huggingface/datasets/blob/master/CONTRIBUTING.md#how-to-contribute-to-the-dataset-cards)
+The dataset is released under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/) license.
 
 ### Citation Information
 
@@ -184,10 +184,8 @@ The data fields are the same among all splits.
       journal   = {arXiv:1910.11473v2},
       year      = {2020},
 }
-
 ```
 
-
 ### Contributions
 
-Thanks to [@thomwolf](https://github.com/thomwolf), [@patrickvonplaten](https://github.com/patrickvonplaten), [@lewtun](https://github.com/lewtun) for adding this dataset.
+Thanks to [@thomwolf](https://github.com/thomwolf), [@patrickvonplaten](https://github.com/patrickvonplaten), [@lewtun](https://github.com/lewtun) for adding this dataset.