Add link to paper

This PR ensures the model can be viewed from https://huggingface.co/papers/2012.02110

README.md

@@ -17,7 +17,7 @@ GottBERT is the first German-only RoBERTa model, pre-trained on the German porti
 - **Large Model**: 24 layers, 355 million parameters
 - **License**: MIT
 
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+This was presented in [GottBERT: a pure German Language Model](https://huggingface.co/papers/2012.02110).
 
 ## Pretraining Details