URL in description and README broken

The URL in the repository description and the one in the README are pointing to githubschool's copy of the game instead of yours.

Please fix both so they point to your copy of the game at https://githubschool.github.io/github-games-liliu2020

更新 repository 描述和 README 中的 URL，使两者都指向 https://githubschool.github.io/github-games-liliu2020。首先打开 repository 设置和 README，然后确认两个链接使用的是游戏的副本，而不是 githubschool 的副本。

由索引模型根据 Issue 内容生成。