Add Contributing.md file

[Kerin]

I think it is important to have contributing guidelines so that an open-source contributor know how to contribute properly.
Can I work on this?

[Yash Gautam]

I want to work on this issue

[Madhav Rathi]

Please go ahead. Assigning this issue to @Kerveyfelix as she mentioned it first. @yashgautam9274 Feel free to work on open issues or open your new ones as well. Cheers !!

[Musavveer Rehaman]

I would like to work on it.
Please assign it to me @madhavrathi