Demo link hosted on Heroku is not working

[akcozlem]

The demo link mentioned in the README does not seem to be working.

When opening the following URL:
https://simplest-react-todo-app.herokuapp.com/

An error page is displayed and the application does not load.

This may confuse users who want to quickly try the application.
It might be helpful to update the demo link or remove it from the README if it is no longer maintained.