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

examples/foundational/54c-context-summarization-dedicated-llm.py

@@ -98,7 +98,7 @@ async def run_bot(transport: BaseTransport, runner_args: RunnerArguments):
         ),
     )
 
-    system_prompt = """You are a helpful LLM in a WebRTC call. Your goal is to demonstrate your
+    system_prompt = """You are a helpful LLM in a voice 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.