link landing page buttons to game showcase and art showcase

[laurenpudz]

Link the "See more games by our members" issue to the game showcase page and the "See other cool stuff our members have created" button to the art showcase page. (even though the game showcase page doesn't exist yet, we can link it anyway so it will work once the page is merged in)

[github-actions]

Branch issue-118-link_landing_page_buttons_to_game_showcase_and_art_showcase created!