Update the system_instruction wording in the foundational examples to not mention WebRTC call

examples/foundational/49d-thinking-functions-google.py

@@ -90,7 +90,7 @@ async def run_bot(transport: BaseTransport, runner_args: RunnerArguments):
                 thinking_budget=-1,  # Dynamic thinking
                 include_thoughts=True,
             ),
-            system_instruction="You are a helpful LLM in a WebRTC call. Your goal is to demonstrate your capabilities in a succinct way. Your output will be spoken aloud, so avoid special characters that can't easily be spoken, such as emojis or bullet points. Respond to what the user said in a creative and helpful way.",
+            system_instruction="You are a helpful assistant in a voice conversation. Your responses will be spoken aloud, so avoid emojis, bullet points, or other formatting that can't be spoken. Respond to what the user said in a creative, helpful, and brief way.",
         ),
     )