Merge pull request #215029 from NickCao/zram-fixup

nixos/zram: fix default swapDevices

nixos/modules/config/zram.nix

···
       };
 
       swapDevices = lib.mkOption {
-        default = 0;
-        example = 1;
+        default = 1;
         type = lib.types.int;
         description = lib.mdDoc ''
           Number of zram devices to be used as swap, recommended is 1.