Fix Citation Information section in dataset cards (#4879)

Commit from https://github.com/huggingface/datasets/commit/60bdf3005d1dc0b26da8e5949721b20d932eaad6

README.md

@@ -170,8 +170,14 @@ Data has been sourced from the matriculation exams and online quizzes.
 
 ### Citation Information
 
-[Needs More Information]
-
+```
+@article{hardalov2019beyond,
+  title={Beyond english-only reading comprehension: Experiments in zero-shot multilingual transfer for bulgarian},
+  author={Hardalov, Momchil and Koychev, Ivan and Nakov, Preslav},
+  journal={arXiv preprint arXiv:1908.01519},
+  year={2019}
+}
+```
 
 ### Contributions