add citation

README.md

@@ -143,4 +143,17 @@ Outputs (formatted):
 ```
 scores            75.60  86.60  85.74
 estimated errors  10.48   3.52   0.83
+```
+
+This model is based on the work [Early-Exit and Instant Confidence Translation Quality Estimation](http://arxiv.org/abs/2502.14429) which can be cited as:
+```
+@misc{zouhar2025earlyexitinstantconfidencetranslation,
+      title={Early-Exit and Instant Confidence Translation Quality Estimation}, 
+      author={Vilém Zouhar and Maike Züfle and Beni Egressy and Julius Cheng and Jan Niehues},
+      year={2025},
+      eprint={2502.14429},
+      archivePrefix={arXiv},
+      primaryClass={cs.CL},
+      url={https://arxiv.org/abs/2502.14429}, 
+}
 ```