docs: show estimated quality and cost in example output

README.md

@@ -67,6 +67,7 @@ from router import R2Router
 router = R2Router.from_pretrained(path, embed_url="http://localhost:8000")
 result = router.route_text("What is the capital of France?")
 print(f"Model: {result['model_full_name']}, Budget: {result['token_limit']}")
+print(f"Estimated Quality: {result['predicted_quality']:.3f}, Estimated Cost: ${result['predicted_cost']*1e6:.4f}/1M tokens")
 ```
 
 ### Adjusting Lambda (Cost-Accuracy Tradeoff)