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-penumetch

Update the URL in the README and the repository description, using the destination specified in the issue. Start by checking both locations for the existing GitHub School link. Done means both point to the repository's own game URL; verify the README text and repository description afterward.

索引モデルが issue の本文から書いたものです。