Update README.md (#854)

Author: XdpCs

README.md

@@ -292,7 +292,7 @@
 
 **第1讲：ERC721库：Address, Strings, Context** [代码](https://github.com/AmazingAng/WTF-Solidity/blob/main/Topics/ERC721) | [文章](https://github.com/AmazingAng/WTF-Solidity/tree/main/Topics/ERC721/1_related_libraries/readme.md)
 
-**第2讲：ERC721相关接口** [代码](https://github.com/AmazingAng/WTF-Solidity/blob/main/Topics/ERC721) | [文章](https://mirror.xyz/wtfacademy.eth/4mPkMgHViRjx8OM7TAI-M-2oMfRle36ULzqlpC6S7IQ)
+**第2讲：ERC721相关接口** [代码](https://github.com/AmazingAng/WTF-Solidity/blob/main/Topics/ERC721) | [文章](https://github.com/AmazingAng/WTF-Solidity/tree/main/Topics/ERC721/2_Related_interface/readme.md)
 
 **第3讲：ERC721主合约** [代码](https://github.com/AmazingAng/WTF-Solidity/blob/main/Topics/ERC721/ERC721.sol) | [文章](https://mirror.xyz/wtfacademy.eth/-evZa3S--yw9vVcXfhn9I3UiNRaqWOTLG0eZFFgbcT0)