<NME> README.md
<BEF> ### TeensyUSB code ###

Refer to [Teensyduino instructions](https://www.pjrc.com/teensy/teensyduino.html)
to set up the development environment.

When compiling using Arduino IDE, remember to set the mode to "Serial".

Also check out [this template](https://github.com/apmorton/teensy-template)
for using make and a text editor of your choice for comiling TeensyUSB code.
Also check out [this template](https://github.com/apmorton/teensy-template)
for using make and a text editor of your choice for comiling TeensyUSB code.

<MSG> Update README.md
<DFF> @@ -3,7 +3,10 @@
 Refer to [Teensyduino instructions](https://www.pjrc.com/teensy/teensyduino.html)
 to set up the development environment.
 
-When compiling using Arduino IDE, remember to set the mode to "Serial".
+When compiling using Arduino IDE, remember to set the mode to "Serial + MIDI".
+
+Note: as of this writing the "Serial + MIDI" mode is only available in the beta version of Teensyduiono.
+This mode was added in [this commit](https://github.com/PaulStoffregen/cores/commit/a480cd28da49406c297d241a3cbb535e83bec7eb)
 
 Also check out [this template](https://github.com/apmorton/teensy-template)
 for using make and a text editor of your choice for comiling TeensyUSB code.

Update README.md