message: Add city.names.en, postal.code to City Example in README.md
diff: @@ -214,6 +214,8 @@ Reader.open('/usr/local/share/GeoIP/GeoIP2-City.mmdb').then(reader => {
  const response = reader.city('128.101.101.101');
  console.log(response.country.isoCode); // 'US'
  + console.log(response.city.names.en); // 'Minneapolis'
  + console.log(response.postal.code); // '55407'
  });
  ```
  