add let/in with aliases

modules/homelab/nfs.nix

@@ -2,17 +2,18 @@
 
 # define nfs exports
 let
+  cfg = config.modules.homelab.nfs;
   nfs_exports = ''
     /holocron/vault *(rw,sync,no_subtree_check,no_root_squash)
     /holocron/media *(ro,sync,no_subtree_check)
   '';
 in
 {
-  options = {
-    modules.homelab.nfs.enable = lib.mkEnableOption "enables nfs";
+  options.modules.homelab.nfs = {
+    enable = lib.mkEnableOption "enables nfs";
   };
 
-  config = lib.mkIf config.modules.homelab.nfs.enable {
+  config = lib.mkIf cfg.enable {
     # enable nfs with all exports
     services.nfs = {
       server = {