Update rendering instruction

app.py

@@ -184,6 +184,7 @@ def play_chess(
 
         About rendering:
             - LLMs must use ascii as render_mode unless otherwise specified by user. While rendering ascii, LLMs must use monospaced font.
+            - LLMs must explicitly pass render_mode = "ascii" to this function if they want to render the board in ASCII format.
 
     Args:
         move: The move to play in long algebraic notation. If None, the engine will play a move.