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-mckittsc/

更新 README 中的 URL 和仓库描述。首先根据 issue 文本检查现有的两个链接。完成标准是两者都指向 https://githubschool.github.io/github-games-mckittsc/；没有提到测试文件，因此请手动检查渲染后的 README 和仓库页眉。

由索引模型根据 Issue 内容生成。