message: docs: add links with more details on how to add locales
diff: @@ -160,8 +160,10 @@ use this quick guide:
  - First of all, [create an issue](https://github.com/date-fns/date-fns/issues/new?title=XXX%20language%20support&labels[]=I18n)
  so you won't overlap with others.
  +- A detailed explanation of how to [add a new locale](https://github.com/date-fns/date-fns/blob/master/docs/i18nContributionGuide.md#adding-a-new-locale).
  - Use [English locale](https://github.com/date-fns/date-fns/tree/master/src/locale/en)
  as the basis and then incrementally adjust the tests and the code.
  +- Directions on [adding a locale with the same language as another locale](https://github.com/date-fns/date-fns/blob/master/docs/i18nContributionGuide.md#creating-a-locale-with-the-same-language-as-another-locale).
  - If you have questions or need guidance, leave a comment in the issue.
  Thank you for your support!
  