Describe systemd-boot support

Signed-off-by: Benoit Donneaux <benoit@leastauthority.com>

nixos/modules/100tb.nix

@@ -73,7 +73,7 @@ let
     systemd-boot = lib.mkOption
     { type = lib.types.bool;
       default = false;
-      description = "Fill later";
+      description = "Whether to enable the systemd-boot (formerly gummiboot) EFI boot manager";
     };
 
   };
@@ -111,7 +111,7 @@ in {
   { boot.loader.grub.enable = true;
     boot.loader.grub.version = 2;
     boot.loader.grub.device = if cfg.grubDeviceID == "nodev"  then "nodev" else "/dev/disk/by-id/${cfg.grubDeviceID}";
-    boot.loader.systemd-boot.enable = cfg.systemd-boot; 
+    boot.loader.systemd-boot.enable = cfg.systemd-boot;
     boot.loader.timeout = 10;
     networking.firewall.enable = false;