modules/fs: remove unused symlink.targetName option

modules/fs/default.nix

@@ -103,19 +103,16 @@ let
         default = null;
         description = "create a file in the /nix/store with the provided text and use that as the target";
       };
-      targetName = mkOption {
-        type = types.str;
-        default = path-lib.leaf path;
-        description = "name of file to create if generated from text";
-      };
     };
-    config = {
+    config = let
+      name = path-lib.leaf path;
+    in {
       target = lib.mkIf (config.text != null) (
         (pkgs.writeTextFile {
-          name = path-lib.leaf path;
+          inherit name;
           text = config.text;
-          destination = "/${config.targetName}";
-        }) + "/${config.targetName}"
+          destination = "/${name}";
+        }) + "/${name}"
       );
     };
   });