Yeah, there has been a major reworking of the command line interface since the 0.1.10 release came out. The readme you see at the home page is for the development version of the tool, so it reflects the new interface. You can see the readme for the release version of the tool here:
Work is in progress now to provide an easy means to get the documentation associated with each future release on a nice website:
https://arduino.github.io/arduino-fwuploader/
Great work! Thanks for taking the time to post an update with your findings.