Set up encrypted boot

[jakeisnt]

My disk isn't at all encrypted on boot now.

This isn't a huge priority issue but it would be helpful to encrypt everything, especially on my VPS - where the provider has the potential to access all of my data if it isn't.

[jakeisnt]

https://gist.github.com/martijnvermaat/76f2e24d0239470dd71050358b4d5134 https://elvishjerricco.github.io/2018/12/06/encrypted-boot-on-zfs-with-nixos.html

[jakeisnt]

This looks relatively straightforward and should go hand in hand with #15

[jakeisnt]

The instructions here: https://github.com/Luis-Hebendanz/nix-configs seem to demonstrate the setup of LUKS