Add Teensy versions

Author: aknuds1

README.md

@@ -17,7 +17,7 @@
 
 This is not a radio. It is a sample player that behaves like a radio.  
 
-A digital way to simulate the radio-powered compositions of John Cage and Karlheinz Stockhausen as well as Don Buchla's voltage-controlled radio experiments. It uses a [Teensy](https://www.pjrc.com/teensy/) to play files from an SD card to simulate a voltage controlled AM/FM/Shortwave/Time Travel radio. 
+A digital way to simulate the radio-powered compositions of John Cage and Karlheinz Stockhausen as well as Don Buchla's voltage-controlled radio experiments. It uses a [Teensy 3.1/3.2](https://www.pjrc.com/teensy/) to play files from an SD card to simulate a voltage controlled AM/FM/Shortwave/Time Travel radio. 
 
 ####Progress