Add "not fine-tuned" for chat disclaimer.

README.md

@@ -45,4 +45,4 @@ print(tokenizer.decode(outputs[0]))
 
 ## Notice
 
-Zamba is a pretrained base model and therefore does not have any moderation mechanism.
+Zamba is a pretrained base model and therefore does not have any moderation mechanism. In addition, one should not expect good chat performance, as this model was not fine-tuned for chat.