Add sysprompt to prompt example

@kalomaze

said it's needed

README.md

@@ -23,7 +23,9 @@ This is the fourth in a series of models designed to replicate the prose quality
 Model has been Instruct tuned with the ChatML formatting. A typical input would look like this:
 
 ```py
-"""<|im_start|>user
+"""<|im_start|>system
+You are a friendly assistant.<|im_end|>
+<|im_start|>user
 Hi there!<|im_end|>
 <|im_start|>assistant
 Nice to meet you!<|im_end|>