Added Hacken.in to the list

Hacken.in just adopted the contributor covenant. You can find see [Code of Conduct](https://github.com/hacken-in/website/blob/master/CODE_OF_CONDUCT.md) here and a list of all people currently working on this project saying *aye* [here](https://github.com/hacken-in/website/pull/439). You can also find hints to find the file in both the [README.md](https://github.com/hacken-in/website/blob/master/README.md) and the [CONTRIBUTING.md](https://github.com/hacken-in/website/blob/master/CONTRIBUTING.md) files.