URL in description and README broken

The URL in the repository description and 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-mtsabino/

Inspect the repository description and README to find both existing game URLs. Update each to point to the URL specified in the issue, then verify that the description and README show the same destination.

索引モデルが issue の本文から書いたものです。