Add FAQ entry for "Got bad greeting from SMTP host"

[jmehrens]

Per #109 the error seen was:

[07-09-2023 18:46:26][AP-Web][WARN] Details: Got bad greeting from SMTP host: localhost, port: 465, response: [EOF]
[07-09-2023 18:46:26][AP-Web][WARN] Type: jakarta.mail.MessagingException
[07-09-2023 18:46:26][AP-Web][WARN] Stacktrace: 
[07-09-2023 18:46:26][AP-Web][WARN] org.eclipse.angus.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:2231)
[07-09-2023 18:46:26][AP-Web][WARN] org.eclipse.angus.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:729)
[07-09-2023 18:46:26][AP-Web][WARN] jakarta.mail.Service.connect(Service.java:345)
[07-09-2023 18:46:26][AP-Web][WARN] jakarta.mail.Service.connect(Service.java:225)
[07-09-2023 18:46:26][AP-Web][WARN] jakarta.mail.Service.connect(Service.java:246)
[07-09-2023 18:46:26][AP-Web][WARN] jakarta.mail.Transport.send0(Transport.java:230)
[07-09-2023 18:46:26][AP-Web][WARN] jakarta.mail.Transport.send(Transport.java:152)

Setting mail.smtp.ssl.enable=true fixed the issue.

1. Add a FAQ entry for Got bad greeting from SMTP host: <host>, port: <port>, response: [EOF]
2. Add some details explaining that the server most likely expected an SSL connection instead of TLS.
3. Explain that the resolution is to add mail.smtp.ssl.enable=true and remove mail.smtp.starttls.enable=true