Document Open Source Code of Conduct

[kabirbaidhya]

Take reference from these:

• https://opensource.microsoft.com/codeofconduct/
• https://github.com/facebook/componentkit/blob/master/CODE_OF_CONDUCT.md
• and many others

[jasperdanan]

Would like to take on this issue

[kabirbaidhya]

Hey @jasperdanan Thank you for your interest and willingness to help.
However, this is something we ourselves need to take a crack on first - before we take contributions from others.
If you're willing to contribute, here's one issue that you take #4 for now.