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-clgx-itsybulin/

Update the repository description and the URL in README, replacing the githubschool copy link with https://githubschool.github.io/github-games-clgx-itsybulin/. Check both locations after editing and confirm they point to the repository's game page.

索引モデルが issue の本文から書いたものです。