Complete the mlqa dataset card (#4809)

* Added more details to dataset card of mlqa dataset

* added license and other required details to mlqa

* Modified dataset card of mlqa dataset

Changed language creators tag in dataset card of mlqa dataset to crowdsourced.

Commit from https://github.com/huggingface/datasets/commit/8a9b3cb2a31c9b5306e5ae68b33565934180aefe

README.md

@@ -2,6 +2,28 @@
 pretty_name: MLQA (MultiLingual Question Answering)
 language:
 - en
+- de
+- es
+- ar
+- zh
+- vi
+- hi
+license:
+- cc-by-sa-3.0
+source_datasets:
+- original
+size_categories:
+- 10K<n<100K
+language_creators:
+- crowdsourced
+annotations_creators:
+- crowdsourced
+multilinguality:
+- multilingual
+task_categories:
+- question-answering 
+task_ids:
+- extractive-qa
 paperswithcode_id: mlqa
 ---
 
@@ -54,7 +76,7 @@ paperswithcode_id: mlqa
 
 ### Languages
 
-[More Information Needed](https://github.com/huggingface/datasets/blob/master/CONTRIBUTING.md#how-to-contribute-to-the-dataset-cards)
+MLQA contains QA instances in 7 languages, English, Arabic, German, Spanish, Hindi, Vietnamese and Simplified Chinese.
 
 ## Dataset Structure
 
@@ -227,10 +249,11 @@ The data fields are the same among all splits.
 
 ```
 @article{lewis2019mlqa,
-  title={MLQA: Evaluating Cross-lingual Extractive Question Answering},
-  author={Lewis, Patrick and Oguz, Barlas and Rinott, Ruty and Riedel, Sebastian and Schwenk, Holger},
-  journal={arXiv preprint arXiv:1910.07475},
-  year={2019}
+  title = {MLQA: Evaluating Cross-lingual Extractive Question Answering},
+  author = {Lewis, Patrick and Oguz, Barlas and Rinott, Ruty and Riedel, Sebastian and Schwenk, Holger},
+  journal = {arXiv preprint arXiv:1910.07475},
+  year = 2019,
+  eid = {arXiv: 1910.07475}
 }
 
 ```
@@ -238,4 +261,4 @@ The data fields are the same among all splits.
 
 ### Contributions
 
-Thanks to [@patrickvonplaten](https://github.com/patrickvonplaten), [@M-Salti](https://github.com/M-Salti), [@lewtun](https://github.com/lewtun), [@thomwolf](https://github.com/thomwolf), [@mariamabarham](https://github.com/mariamabarham), [@lhoestq](https://github.com/lhoestq) for adding this dataset.
+Thanks to [@patrickvonplaten](https://github.com/patrickvonplaten), [@M-Salti](https://github.com/M-Salti), [@lewtun](https://github.com/lewtun), [@thomwolf](https://github.com/thomwolf), [@mariamabarham](https://github.com/mariamabarham), [@lhoestq](https://github.com/lhoestq) for adding this dataset.