nixos/wordpress: Mention a theme and plugin packaging tool in the docs.

nixos/modules/services/web-apps/wordpress.nix

@@ -127,7 +127,7 @@ let
  default = [];
  description = ''
  List of path(s) to respective plugin(s) which are copied from the 'plugins' directory.
- <note><para>These plugins need to be packaged before use, see example.</para></note>
+ <note><para>These plugins need to be packaged before use, see example. Using something like https://git.helsinki.tools/helsinki-systems/wp4nix may be a better option.</para></note>
  '';
  example = ''
  # Wordpress plugin 'embed-pdf-viewer' installation example
@@ -154,7 +154,7 @@ let
  default = [];
  description = ''
  List of path(s) to respective theme(s) which are copied from the 'theme' directory.
- <note><para>These themes need to be packaged before use, see example.</para></note>
+ <note><para>These themes need to be packaged before use, see example. Using something like https://git.helsinki.tools/helsinki-systems/wp4nix may be a better option.</para></note>
  '';
  example = ''
  # Let's package the responsive theme