Support Nextcloud 29.0.0

This versioned release has been tested to be compatible up to Nextcloud v29.0.0.

This release introduces the following changes:

• improve description of how to configure the recover.php scripts (#41)
• fix typo (#43)
• be more verbose on startup (#44)
• document debug mode (#45)
• align CHANGELOG.md with the release notes (#46)
• fix another typo (#47)
• improve startup sequence (#48)
• Nextcloud 29 release (#49)
• add Nextcloud29 test (#50)