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-rgernhardt

Update the URL in the README and the repository description, as named in the issue. Check both locations against https://githubschool.github.io/github-games-rgernhardt and confirm that each now points to this repository's game copy.

索引モデルが issue の本文から書いたものです。