prepare (and give) training for 2FA with security keys in CR

In #41083 (closed) we agreed to distribute security keys (specifically Yubikeys) in Costa Rica.

This ticket is to ensure we have a training prepared beforehand and that we give it to people and that people are happy.

We should also, incidentally, keep track of the keys to make sure they do end up in CR.

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information