nixos/peroxide: correct option doc

Correct the description for the option services.peroxide.enable.

nixos/modules/services/networking/peroxide.nix

···
 in
 {
   options.services.peroxide = {
-    enable = mkEnableOption (lib.mdDoc "enable");
+    enable = mkEnableOption (lib.mdDoc "peroxide");
 
     package = mkPackageOptionMD pkgs "peroxide" {
       default = [ "peroxide" ];