As often happens, I hear about great new features from Apple, but I have no idea what they do or how to use them because the only information I find from Apple comes in vague sales pitches on the Apple site. So -- iCloud Drive. I assumed this was Apple's version of Dropbox. But it seems that it's limited to syncing mail, contacts, etc. And, according to what I see in preference, there is a small number of Apple apps that will sync documents to iCloud. And, of course, I don't use them (but that's just me -- I'm sure other people do.) But I can't just move Word docs, spreadsheets, pdfs, etc into iCloud? Or am I missing anything? From what I see, iCloud Drive is pretty much useless.