change link in about page

change the link in about page from https://zz-zye.github.io/suneng/ to https://zyeworld.github.io/KoreanSAT-math/

<img width="333" height="187" alt="Image" src="https://github.com/user-attachments/assets/9409e66f-cbd9-4b96-8313-65ef00d0da75" />