Submit SecureDrop repos for forgoodfirstissue

*(Text copied from an internal issue by @legoktm)*

https://github.com/github/forgoodfirstissue

We should submit the SD repos towards this so they'll show up in GitHub's list for new(er) developers. I think/hope it'll
be pretty straightforward.

https://github.blog/open-source/social-impact/for-good-first-issue-introducing-a-new-way-to-contribute/