Improvements needed in Contribute section of README

[shashaBot]

The contribute section of README is highly lacking. The steps demonstrate how to run the application with the current state of the repo but doesn't help very much with contribution part. For example, it doesn't include how to make the changes and making a pull request from the contributor's fork (I think that's the model being followed).

Opening this issue to discuss how to approach this. We can go multiple ways: improving the section under README or creating a new CONTRIBUTING doc with more extensive branch policies, pull request template.

[poush]

Inspiration can be taken from: https://github.com/fossasia/open-event-server#contributions-best-practices

parent issue: #36