Added documentation and changed import to not only allow 'validate' function

lib/sukaato/custom_validators.ex

@@ -1,7 +1,15 @@
 defmodule Sukaato.CustomValidators do
   import Ecto.Changeset
-  import Validate, only: [validate: 2]
+  import Validate
 
+  @moduledoc """
+  Provide a collecton of custom validation functions for Ecto database
+  database table update validation.
+  """
+
+  @doc """
+  Validate a map or array/list column for an Ecto database table update.
+  """
   def validate_map_format(changeset, field, conventional_mapping) when is_atom(field) do
     field_value = get_field(changeset, field)
     validation_result = validate(field_value, conventional_mapping)