README: add installation guide

README.md

@@ -1,5 +1,28 @@
 This repo is managed with Nix + GNU stow
 
+# Installation Guide (for myself & those who are interested)
+- Generate image & boot
+  We do this because the default one doesn't have all the utilities we want (e.g. disko).
+  - generate image `nix build .#nixosConfigurations.installer.config.system.build.isoImage`
+  - `dd` the image to a flash drive (remember to `sync`)
+  - boot off that flash drive
+
+- Format disk (DANGER)
+  - modify the disko file to point to the disk to be formatted
+
+- Installation (iirc the disko auto install has some issues)
+  ```bash
+  # Are you sure the disko config has the right drive path?
+  disko -- -m disko ./disko.nix # format the drive
+
+  # optional for unknown hard ware
+  nixos-generate-config --no-filesystems --root /mnt --dir . # disko will take care of the file system configuration
+  # put the generated config in the right path and import it
+
+  nixos-install --flake .dotfiles#<hostname>
+  # profit
+  ```
+
 # Hosts
 - vanadium: Framework 13 (AMD 7040 Series)
 - tungsten: MacBook Air 2014 (because it gets really hot)