update readme with disko steps

README.md

@@ -5,11 +5,33 @@ Declarative configuration of my machines & dotfiles.
 > [!WARNING]
 > Still a work-in-progress!
 
-## Installation
+## Setup
+
+The following requires custom boot media built from manifests under
+`installer/`.
+
+To build the install-usb media, run
+
+```sh
+just build-iso
+```
+
+### Init Drives
+
+```sh
+echo -n "<luks-secret-key>" > /tmp/secret.key
+# set up the drive partitions
+sudo just disko-init <host>
+# mount the drives so that you can perform nix installation
+sudo just disko-mount <host>
+```
+
+### Init Install
+
 ```sh
 git clone https://github.com/otosky/nix-config
 cd nix-config
-nixos-install --root /mnt --flake .#ot-desktop
+sudo nixos-install --root /mnt --flake .#ot-desktop
 ```
 
 ## Rebuilds