Country superstar Shania Twain announced via a Facebook posting Tuesday that she is canceling a couple of tour dates on what is being billed as her final tour ever.   "Shania Twains Rock This Country Tour dates at the Verizon Wireless Arena on October 6th in Manchester, NH and the Times Union Center on October 7th in Albany, NY have been cancelled due to illness," the post reads. "Shania Twains doctors have advised her to rest for several days after she was diagnosed with a respiratory infection."  Unfortunately, fans in those cities may miss out on their last chance to see Twain as she will reportedly not re-schedule those shows.  Twain's Rock This Country tour is slated to resume on Friday, October 9th at the Videotron Centre in Quebec.  Click Here for a rundown of the singer's remaining tour stops.