Missing contributing guide

[Aman Garg]

Hey there, thanks for the useful project.

As it stands today, there's no CONTRIBUTING.md guide for the project today.
It'd be great if we could add it so it becomes easier to develop and contribute upstream.

[ktr]

Thanks for your feedback! It'd be a very useful resource for first-time contributors.
We'll add CONTRIBUTING.md in the near future.

[Aman Garg]

Thanks.