update compatibility matrix in README

Author: andydoro

README.md

@@ -29,7 +29,7 @@ MCU                | Tested Works | Doesn't Work | Not Tested  | Notes
 ------------------ | :----------: | :----------: | :---------: | -----
 Atmega328 @ 16MHz  |      X       |             |            | 
 Atmega328 @ 12MHz  |      X       |             |            | 
-Atmega32u4 @ 16MHz |             |             |     X       | 
+Atmega32u4 @ 16MHz |      X       |             |            | 
 Atmega32u4 @ 8MHz  |             |             |     X       | 
 ESP8266            |             |             |     X       | 
 Atmega2560 @ 16MHz |             |             |     X       |