hide ForDialyzer module in hexdocs

Author: hlindset

mix/for_dialyzer.ex

@@ -1,4 +1,6 @@
 defmodule ForDialyzer do
+  @moduledoc false
+
   # Juse to exorcise dialyzer errors. This module is not included
   # in the library published to hex.pm.
 
@@ -43,4 +45,4 @@ defmodule ForDialyzer do
     small_kip = Image.open!("./test/support/images/Kip_small.jpg")
     _ = Image.k_means(small_kip)
   end
-end
+end