Remove exposed Heroku endpoints

[Raghuboi]

I recently updated one of my repositories (Multiplayer Poker Game) that used socket.io and similar server infrastructure. From my understanding WebSockets will not be supported out of the box in Heroku's free accounts anymore. I personally moved my server over to render.com which has free hosting

Since Heroku won't be used for this repo anymore I suggest removing your Heroku endpoints from the code and readme to avoid confusion for new users. Possibly also using environment variables as a good practice. I can volunteer to take this task on.

More on Heroku discontinuing free tiers:
https://blog.heroku.com/next-chapter

[Raghuboi]

@mizanxali