Add citation information

We asked the authors about their citation information: https://github.com/SpellOnYou/korean-sarcasm/issues/2

They updated their repo: https://github.com/SpellOnYou/korean-sarcasm/commit/286aaf8acbe0df0cadd6e2c6635d507ca6ddc9d7

README.md

@@ -162,7 +162,16 @@ This dataset is licensed under the MIT License.
 
 ### Citation Information
 
-Unknown citation information: https://github.com/SpellOnYou/korean-sarcasm
+```
+@misc{kim2019kocasm,
+  author = {Kim, Jiwon and Cho, Won Ik},
+  title = {Kocasm: Korean Automatic Sarcasm Detection},
+  year = {2019},
+  publisher = {GitHub},
+  journal = {GitHub repository},
+  howpublished = {\url{https://github.com/SpellOnYou/korean-sarcasm}}
+}
+```
 
 ### Contributions