Update README.md

README.md

@@ -4,4 +4,4 @@ license: mit
 
 This model has been first pretrained on the BEIR corpus and fine-tuned on the MS MARCO dataset following the approach described in the paper **COCO-DR: Combating Distribution Shifts in Zero-Shot Dense Retrieval with Contrastive and Distributionally Robust Learning**. The associated GitHub repository is available here https://github.com/OpenMatch/COCO-DR.
 
-This model is trained with BERT-large as the backbone with 335M hyperparameters.
+This model is trained with BERT-large as the backbone with 335M hyperparameters. See the paper https://arxiv.org/abs/2210.15212 for details.