Update README.md

Dear repository author,
I wanted to take a moment to express how impressed I am with your model. It's truly outstanding and has shown great performance. I am writing to indicate my interest in contributing to the README of your model. Specifically, I would like to update the base_model information to enhance the documentation. This is to address the gap in the model card and ensure users have complete, accurate information.
Thank you for your attention to this matter.

README.md

@@ -25,6 +25,8 @@ model-index:
     metrics:
     - type: pass@1
       value: 44.3
+base_model:
+- bigcode/starcoder2-15b
 ---
 
 # starcoder2-15b-quantized.w8a16