Documentation Cleanup - Repetition in SMTP Troubleshooting Section

In an effort to aid those responsible for managing the awesome Nextcloud official support docs, it appears there may be two areas stating identical information, which could be merged under one heading.

By no means anything major, just trying to be helpful, to a greatly helpful organization.

Cheers, -Ian

Also, the entry says to use:

“mail_smtpdebug” => true;

but that little ; created some “Internal Server Error” issues, so perhaps a “,”?

Indeed we could simplify this. Mind sending a pull request to GitHub - nextcloud/documentation: 📘 Nextcloud documentation?