Yes Apple Cider Vinegar will work just as great as plain vinegar when cleaning your Keurig or any other coffee maker.
The method of cleaning A regular coffee maker or Keurig coffee maker is the same as you would with Vinegar.
Just pour the apple cider vinegar into the Keurig or Coffee Maker and run the machine like you would to make coffee and then flush it out once or twice with plain water.
You may have to run the coffee maker or Keurig Coffee maker through a few cycles with water to clean the Apple Cider Vinegar out of the coffee maker or Keurig.