Hi Divyendu!
Thank you so much for letting me know about the broken link! I'll look into it, and update this answer accordingly!
Meanwhile, you can clone the learn-draftjs repo; to run a local instance of the application.
To run learn-draftjs locally, run the following commands in your terminal!
$ git clone git@github.com:fatman-/learn-draftjs.git
$ cd learn-draftjs
$ npm install
$ npm start
If everything works properly, you can visit localhost:3000 to start learning DraftJS!