Document Authenticating against Microsoft / Office365 Mail Servers (Graph)

- due to [Exchange Online to retire Basic auth for Client Submission (SMTP AUTH)](https://techcommunity.microsoft.com/blog/exchange/exchange-online-to-retire-basic-auth-for-client-submission-smtp-auth/4114750)
- see also https://github.com/metasfresh/me03/issues/23221