Integrate All-Contributors spec

[Ryan-Gordon]

taken from all-contributors repo : The basic idea is this:

Use the project README (or other prominent public documentation page in the project) to recognize the contributions of members of the project community. People are giving of themselves and their free time to contribute to open source projects in so many ways. It can be a real time sink sometimes and so they should be praised for all their contributions (code or not).

https://github.com/kentcdodds/all-contributors