Update README.md

README.md

-# Hörner, J., Voigt, A., Braun, C. (2021). Snowball Earth initiation and the thermodynamics of sea ice. Journal of Advances in Modeling Earth Systems (submitted).
+# Hörner, J., Voigt, A., Braun, C. (2022). Snowball Earth initiation and the thermodynamics of sea ice. Journal of Advances in Modeling Earth Systems (submitted).
 
 Code repository for ICON runscripts and python post processing scripts used in the analysis.