[c-lightning] Updated Developer Meeting Invitation

[Rusty Russell]

Hi all,

        This ICS file should have the correct times and updated
Jitsi link for the bi-weekly Core Lightning developer chats (in
line with our recent rebranding).

        https://meet.jit.si/Core-Lightning-Open-Meeting

It's 5:30am Adelaide Time every two weeks (Tuesday morning here, Monday
for almost everyone else), which moves with Daylight Saving of course;
sorry for you Europeans but that's as early as I can function!

Cheers,
Rusty.