update citation of paper

Author: marta-seq

README.md

@@ -123,7 +123,7 @@ You can also use directly PENGUIN functions. Just check pipeline files.
 If you find this repository useful in your research or for educational purposes please refer to:
 Sequeira, A. M., Ijsselsteijn, M. E., Rocha, M., & de Miranda, N. F. (2024). PENGUIN: a rapid and efficient image 
 preprocessing tool for multiplexed spatial proteomics. Computational and Structural Biotechnology Journal, 23, 3920-3928.
-DOI: 10.1016/j.csbj.2024.10.048 . 
+doi:https://doi.org/10.1016/j.csbj.2024.10.048