add hardware-notes module for documentation

Fixes #3

lib/hardware-notes.nix

@@ -0,0 +1,45 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  # use tail recursion to prevent whitespace padding
+  mkLog = list:
+    let
+      head = builtins.head list;
+      tail = builtins.tail list;
+    in
+    ''
+      # ${head.title}
+      ${head.text}${if tail == [] then "" else "\n\n${mkLog tail}"}
+    '';
+in
+
+{
+
+  options = {
+    hardwareNotes = mkOption {
+      internal = true;
+      type = types.listOf types.optionSet;
+      options = {
+        title = mkOption {
+          type = types.str;
+          example = "Thunkpad-2000: increase self-destruct timeout";
+        };
+        text = mkOption {
+	  type = types.str;
+          example =
+            ''
+              Increase security timeout at boot using platform managment
+              tool to prevent premature data loss.
+            '';
+        };
+      };
+    };
+  };
+
+  config = {
+    environment.etc."hardware-notes".text = mkLog config.hardwareNotes;
+  };
+
+}