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

examples/foundational/48-service-switcher.py

@@ -114,7 +114,7 @@ async def run_bot(transport: BaseTransport, runner_args: RunnerArguments):
     # Uses ServiceSwitcherStrategyManual by default
     tts_switcher = ServiceSwitcher(services=[tts_cartesia, tts_deepgram])
 
-    system_prompt = "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_prompt = "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."
 
     llm_openai = OpenAILLMService(
         api_key=os.getenv("OPENAI_API_KEY"),