Added more documentation to uploads and delete methods
Added more documentation to uploads and delete methods

- Added more information about how the upload/delete multiple files queue works
- Added more information about how the progress handler works

Signed-off-by: NicoleYarroch <5fee00239940f883d4c2854e41c7f989e75278a3@livio.io>

smartdevicelink/sdl_ios,kshala-ford/sdl_ios,APCVSRepo/sdl_ios,FordDev/sdl_ios,FordDev/sdl_ios,kshala-ford/sdl_ios,APCVSRepo/sdl_ios,kshala-ford/sdl_ios,kshala-ford/sdl_ios,APCVSRepo/sdl_ios,FordDev/sdl_ios,smartdevicelink/sdl_ios,FordDev/sdl_ios,smartdevicelink/sdl_ios,APCVSRepo/sdl_ios,FordDev/sdl_ios,smartdevicelink/sdl_ios,kshala-ford/sdl_ios,smartdevicelink/sdl_ios,APCVSRepo/sdl_ios