Ongoing - document the history and progress of the data sets in the wiki

## Goal
Make it easier for others to get up to speed on what has been learned from datasets and what is still unknown

## Why
As tasks in the data team change hands over time, we've been spending a lot of time trying to re-learn. Given the amount of effort that goes into researching and understanding the laws, it's valuable to capture/share that information.

## Notes
- This looks like a good wiki page for documenting the data history: https://github.com/codeforboston/clean-slate/wiki/Data:-Expungement-Analysis
- This is likely an ongoing task that everyone on the data team can contribute to as we go along.