L1: notes中有2处非常非常非常小的笔误

<img width="2040" height="912" alt="Image" src="https://github.com/user-attachments/assets/ea8fb3fe-a32e-460f-a54e-8e00651716e7" />

↑此处1，-1反了

<img width="1527" height="901" alt="Image" src="https://github.com/user-attachments/assets/d9f8def5-82c0-4177-926b-58b4106616af" />

↑注释有误，sigmoid函数不传入列表

