people: Policy on alumni links?

[effigies]

I think some alumni entries got stripped of their ORCID/GitHub when being moved from current positions, but Martin still has his:

Do we have a policy, or is it on request of the alumnus? My personal inclination would be to preserve ORCIDs, which will generally remain updated as long as someone is at least academic-adjacent, and might be more up-to-date than the "website" link.

[poldrack]

we should definitely keep whatever links they have (and I agree that ORCID is the best, but any others are fine too)

[effigies]

Restored some fields that were lost in 907aa53 as part of #89.