Add citation

README.md

@@ -69,4 +69,17 @@ The annotation was performed by a single annotator.
 | – `PER`              |  104 |    92 |    93 |   118 |   407 |
 | – `ORG`              |  193 |   216 |   266 |   227 |   902 |
 | – `LOC`              |  182 |   167 |   197 |   246 |   792 |
-| – `MISC`             |  113 |    79 |    88 |    39 |   319 |
+| – `MISC`             |  113 |    79 |    88 |    39 |   319 |
+
+## Citation
+```bibtex
+@article{vamvas-etal-2023-swissbert,
+      title={Swiss{BERT}: The Multilingual Language Model for Switzerland}, 
+      author={Jannis Vamvas and Johannes Gra\"en and Rico Sennrich},
+      year={2023},
+      eprint={2303.13310},
+      archivePrefix={arXiv},
+      primaryClass={cs.CL},
+      url={https://arxiv.org/abs/2303.13310}
+}
+```