Create notebook to generate a list of recently active participants so we can thank them

[mialondon]

I currently do this manually based on the list of recent participants on the dashboard, but I don't know if it includes everyone who's recently contributed and it's a bit of a faff to deduplicate and shorten surnames to an initial.

This could possibly be based on existing notebooks e.g. https://github.com/LibCrowds/notebooks

[mialondon]

@harryjmoss I've put this in an issue to make it easier to track / share links etc