Update README.md

README.md

@@ -20,6 +20,6 @@ data = data["train"]
 ## 1: データ型をtorchへ
 ```py
 from datasets import Dataset
-train = Dataset.from_dict(data[slice(0, 400, None)])
+train = Dataset.from_dict(data[slice(0, 400, None)]) // 訓練データとして400枚ほど抽出
 train = train.with_format("torch")
 ```