Code snippet error in "Running Agents" document (#1665)

Author: iliailmer

docs/running_agents.md

@@ -100,6 +100,7 @@ async def main():
     # Create session instance
     session = SQLiteSession("conversation_123")
 
+    thread_id = "thread_123"  # Example thread ID
     with trace(workflow_name="Conversation", group_id=thread_id):
         # First turn
         result = await Runner.run(agent, "What city is the Golden Gate Bridge in?", session=session)