Update README.md

The BioMistral model is truly impressive! We would love to contribute by updating the README to include the base_model information. This will help address the current gap in the model card.

README.md

@@ -14,6 +14,8 @@ pipeline_tag: text-generation
 tags:
 - medical
 - biology
+base_model:
+- mistralai/Mistral-7B-Instruct-v0.1
 ---