update upcoming agenda and meeting notes links

[DerekNonGeneric]

Just trying to keep the links to these updated with this for now, but imagine these PRs could be automated at some point.

Thankfully I have only had to do this once so far. :)

[smorimoto]

@DerekNonGeneric I'm not sure if it's really up to date or just one prior to the latest, or if you're suggesting future notes with a time machine, but I trust you and just merge this. Thank you!

[DerekNonGeneric]

I'm not sure if it's really up to date or just one prior to the latest […]

Yeah, it is a little confusing! This PR updated it to the most up-to-date content available for both items. The link to “Recent Meeting Notes” currently points to the one prior to the most-recent meeting.

The most recent meeting took place in San Francisco less than two weeks ago; hence, no recent meeting notes yet available as that seems to be the usual turnaround time (~a couple of weeks unless they are late).

Ideally, “Recent Meeting Notes” would link to the most recent meetings' notes, while “Upcoming Agenda” would link to the agenda for the next meeting(s) coming up that have yet to take place. I wonder what would be preferable: always having the most up-to-date links or previous one/next one as it was likely originally intended. The meeting cadence seems to have changed since this idea was first implemented, which now allows for the “Recent Meeting Notes” link to lag behind like this a bit more noticeably.

TC39 has updated its process to have 8 meetings a year, instead of the usual 6, with 4 regular length meetings and 4 short two-day meetings.
— https://spidermonkey.dev/blog/2021/03/18/tc39.html

Either way, I should have a PR tackling #91 via automation pretty soon where folks can voice their preference (if they have any).