Add a note about ATmega32U4 incompatibility to SerialEvent example

per1234 · cmaglie · commit 4026b916d300 · 2017-07-07T00:38:15.000+02:00
serialEvent() does not work on the ATmega32U4 boards. Reference: https://github.com/arduino/Arduino/issues/1031
diff --git a/examples/04.Communication/SerialEvent/SerialEvent.ino b/examples/04.Communication/SerialEvent/SerialEvent.ino
@@ -8,6 +8,9 @@
  A good test for this is to try it with a GPS receiver
  that sends out NMEA 0183 sentences.
 
+ NOTE: The serialEvent() feature is not available on the
+ Leonardo, Micro, or other ATmega32U4 based boards.
+ 
  Created 9 May 2011
  by Tom Igoe
 
