Document the hosts/ folder

hosts/README.md

+# Host configuration
+
+This folder contains the system configuraiton for each host.
+
+## Structure
+```
+└── hosts/                          # Hosts covered by these nixfiles
+   ├── e151/                        # Lenovo TinkPad E15 (1)
+   │  ├── configuration.nix         # Host configuration
+   │  ├── networking.nix            # Networking configuration
+   │  └── hardware-configration.nix # Hardware configuration generated by nixos-generate-config(8)
+   │
+   └── e152/                        # Lenovo Thinkpad E15 (2)
+      ├── configuration.nix         # Host configuration
+      ├── networking.nix            # Networking configuration
+      └── hardware-configration.nix # Hardware configuration generated by nixos-generate-config(8)
+```
+
+## Adding a new host
+
+For a new host $HOSTNAME Copy one of the subfolders to a new subfolder $HOSTNAME and adapt the configuration to your liking. Don't forget to include the generated `hardware-configuration.nix` from [nixos-generate-config(8)](https://www.mankier.com/8/nixos-generate-config)

hosts/e151/configuration.nix

@@ -9,8 +9,10 @@
   ];
 
   # Use the systemd-boot EFI boot loader.
-  boot.loader.systemd-boot.enable = true;
-  boot.loader.efi.canTouchEfiVariables = true;
+  boot.loader = {
+    systemd-boot.enable = true;
+    efi.canTouchEfiVariables = true;
+  };
 
   # This value determines the NixOS release from which the default
   # settings for stateful data, like file locations and database versions

hosts/e151/networking.nix

-{ config, pkgs, ... }:
+{ pkgs, ... }:
 
 {
   networking = {

hosts/e152/configuration.nix

@@ -9,8 +9,10 @@
   ];
 
   # Use the systemd-boot EFI boot loader.
-  boot.loader.systemd-boot.enable = true;
-  boot.loader.efi.canTouchEfiVariables = true;
+  boot.loader = {
+    systemd-boot.enable = true;
+    efi.canTouchEfiVariables = true;
+  };
 
   # This value determines the NixOS release from which the default
   # settings for stateful data, like file locations and database versions

hosts/e152/networking.nix

-{ config, pkgs, ... }:
+{ pkgs, ... }:
 
 {
   networking = {