Added github_url to topic/riot-games

Source: https://www.riotgames.com/en/DevRel/new-comms#:~:text=IS%20LIVE%20NOW.-,https%3A//github.com/RiotGames/developer%2Drelations,-To%20report%20an

Author: mikaeldui

topics/riot-games/index.md

@@ -4,6 +4,7 @@ created_by: Brandon Beck, Marc Merrill
 display_name: Riot Games
 logo: riot-games.png
 related: league-of-legends, legends-of-runeterra, teamfight-tactics, valorant, league-of-legends-wild-rift
+github_url: https://github.com/RiotGames
 released: September 2006
 short_description: Riot Games, Inc. is an American video game developer, publisher and esports tournament organizer.
 topic: riot-games