Add attribution links to each example description

[calebfoss]

I used the Github API to pull the blame for each example with Github username data. I then mapped that data to links and added them to the descriptions for each example. Finally, I made some manual tweaks based on contributors that were missing from the blame, such as @Malayvasa who contributed examples via p5 editor links.

[Qianqianye]

Thanks @calebfoss. I'm still waiting for some previous contributors' feedback on this issue, like how to properly credit the contributors who worked on p5.js examples prior to the STF project, especially based on the fact that lots of p5.js examples were directly ported from examples on Processing website.

Meanwhile, @SableRaf is looking into getting clarification on processing website repo license issue.

I will come back to this PR after get more response from other contributors.