Added all SEPA countries (IBANs from European Union countries) and minimal test coverage for countries

lib/iban_ex/country/ee.ex

@@ -1,6 +1,13 @@
 defmodule IbanEx.Country.EE do
   @moduledoc """
   Estonian IBAN parsing rules
+
+  ## Examples
+
+    iex> %IbanEx.Iban{country_code: "EE", check_digits: "38", bank_code: "22", branch_code: "00", national_check: "5", account_number: "22102014568"}
+    iex> |> IbanEx.Country.EE.to_string()
+    "EE 38 22 00 22102014568 5"
+
   """
 
   @size 20