MacRumors is reporting that using 'Reset All Settings' deletes some documents stored in iCloud Drive:
In our own testing, using "Reset All Settings" deleted all iWork documents stored in iCloud Drive on the iPhone and on iCloud.com. After allowing time for syncing to a Mac running OS X Yosemite, all of the documents disappeared from that machine as well. Preview and TextEdit documents, which cannot be accessed on the iPhone, remained untouched on the Mac.
So if you have iCloud Drive enabled, it's probably best to avoid using the 'Reset All Settings' function at this time. Note that iCloud Drive is different from Apple's Documents in the Cloud, which iCloud Drive is designed to ultimately replace.