Add artifact purpose

[Wenxin-Jiang]

This is for #1

[davisjam]

I'm a little rusty on my git, but @Wenxin-Jiang if I opened a PR using @HuiyunPeng 's contribution, and this branch also contains that contribution, it seems that some issue may result if we open a PR of this branch against upstream? Maybe we can make a fresh branch, put only the non-Huiyun material into it, with a single commit, and do a PR with that? Or am I overthinking this?

[Wenxin-Jiang]

@davisjam I think it should be fine if we are combining both @HuiyunPeng 's PR and this PR. My understanding is that her PR is now a commit to this branch. Then if we merge to the upstream branch, the PR will include both her (as a sub-PR/commit) and this PR (as the major PR).

If we want to have separate PRs then we should definitely create a new branch, but since her PR is built upon this one, so maybe we want a single PR which simply change the OpenScience file?

[davisjam]

I resolved conflicts locally and opened a PR acmsigsoft#169