add citation information

README.md

@@ -122,3 +122,18 @@ Poro is an advanced language model, primarily optimized for English, Finnish and
 ## License
 
 Poro is released under the Apache 2.0 license.
+
+## Citation
+
+```
+@misc{luukkonen2024poro,
+      title={Poro 34B and the Blessing of Multilinguality}, 
+      author={Risto Luukkonen and Jonathan Burdge and Elaine Zosa and Aarne
+Talman and Ville Komulainen and Väinö Hatanpää and Peter Sarlin and Sampo
+Pyysalo},
+      year={2024},
+      eprint={2404.01856},
+      archivePrefix={arXiv},
+      primaryClass={cs.CL}
+}
+```