Merge pull request "Nano's A6 and A7 can not be used as digital pins" #477 from per1234/nano-a6_a7

Note that the A6 and A7 pins on Nano, Mini and Pro mini can not be used as digital pins.

Author: robsoncouto

Language/Functions/Digital IO/digitalWrite.adoc

@@ -77,7 +77,7 @@ void loop()
 
 [float]
 === Notes and Warnings
-The analog input pins can be used as digital pins, referred to as A0, A1, etc.
+The analog input pins can be used as digital pins, referred to as A0, A1, etc. The exception is the Arduino Nano, Pro Mini, and Mini's A6 and A7 pins, which can only be used as analog inputs.
 
 --
 // HOW TO USE SECTION ENDS