[doc] miss result (#17589)

Signed-off-by: reidliu41 <reid201711@gmail.com>
Co-authored-by: reidliu41 <reid201711@gmail.com>

docs/source/features/quantization/fp8.md

@@ -106,7 +106,7 @@ Load and run the model in `vllm`:
 ```python
 from vllm import LLM
 model = LLM("./Meta-Llama-3-8B-Instruct-FP8-Dynamic")
-model.generate("Hello my name is")
+result = model.generate("Hello my name is")
 print(result[0].outputs[0].text)
 ```