How to contribute new results

[dgarijo]

It is not clear how to contribute a new result to the current ones.

• How should someone contribute a new result
• How can it be compared with existing results

[dgarijo]

I added a section in the README file to address this. However, we need a CONTRIBUTING.md file with more information.

• How to contribute a new onto for the benchmark
• How to compare your results with the ones in the benchmark (this ties to the leaderboards)