Added information about arity and return values to documentation of 'validate_map_format'

lib/sukaato/custom_validators.ex

@@ -8,7 +8,11 @@ defmodule Sukaato.CustomValidators do
   """
 
   @doc """
-  Validate a map or array/list column for an Ecto database table update.
+  Validate a map , array, or list column for an Ecto database table update.
+
+  Arity: 3
+
+  Return Value: changeset || add_err/3
   """
   def validate_map_format(changeset, field, conventional_mapping) when is_atom(field) do
     field_value = get_field(changeset, field)