Add calendar links to schedule

[chris48s]

Each session should ideally have an 'add to calendar' link
Is there a way we can have an 'add all sessions to calendar' link?

One approach might be to link out to an external service for this (e.g: I think google calendar can generate a .ics link which can be consumed by any calendar app) @serahrono - do you maintain the sessions in a calendar application, or is the schedule CSV the only place where these are stored?

If they are only in the CSV, maybe we could template out a .ics file in jekyll

[chris48s]

If we don't farm it out to an external service, here is quite a nice example of how to produce an ICS using jekyll templates:
https://github.com/swcarpentry/website/blob/main/pages/workshops.ics
Doing this would require us to be a bit more robust about how we store the session timestamps in the CSV (refs #113 )

Just thinking about this a bit more, if we do it this way, making an "add all to calendar" link is actually easier than doing it for the individual sessions. To do an individual appointment for each session, each one would need its own template (we could generate them with a GH action).