WIP: add notes for missing persistence/backup

TODO:
* Look at for more inspiration https://github.com/nix-community/impermanence/pull/108
* Do home-manager
* Common files https://github.com/nix-community/impermanence/issues/10
* Useful config: f77271b249/system/modules/impermanence.nix

modules/nixos/hardware/networking/default.nix

@@ -24,6 +24,11 @@ in
       networking.networkmanager.enable = true;
 
       # Persist NetworkManager files
+      my.system.persist.files = [
+        "/var/lib/NetworkManager/secret_key"
+        "/var/lib/NetworkManager/seen-bssids"
+        "/var/lib/NetworkManager/timestamps"
+      ];
       my.system.persist.directories = [
         "/etc/NetworkManager/system-connections"
       ];

modules/nixos/system/printing/default.nix

@@ -65,5 +65,7 @@ in
       # Allow resolution of '.local' addresses
       nssmdns4 = true;
     };
+
+    # FIXME: persistence?
   };
 }