Supervise mode Wiki page references deleted/privated code (link rot)

[aofarrel]

https://github.com/broadinstitute/fiss/wiki/Supervise-Mode references https://github.com/broadinstitute/gdac-firecloud a few times, but this repo appears to not exist anymore. Unfortunately the repo doesn't seem to be on waybackmachine either, so it's a little tricky to follow the given example.