Add a .env.example file

[kashyap-harshit]

Create a .env.example file. It should list all environment variables that need to be set in the actual .env file.

[Gireeshs02]

@kashyap-harshit A PR has been submitted to this issue.
Please review and merge it.

[kashyap-harshit]

please don't make PRs before you get assigned to an issue