chore(ci): make a copy of index.html with name 404.html

[Nikhil1920]

What:

->Now before deploying to github pages we will create a copy of index.html file with the name 404.html
->Because of this all routes will be mapped to our app's index.html

Why this changes are necessary

Now our app will work correctly on refresh or navigating directly using a link instead of github pages showing a 404