update example

Author: RCmags

examples/read_signal/read_signal.ino

@@ -5,7 +5,7 @@
 Servo servo1;
 Servo servo2;
 
-// 1. Each signal must be read with an unsigned int
+// 1. Each signal must be read with an volatile unsigned int
 #include <PulseInput.h>   
 volatile unsigned int input1;
 volatile unsigned int input2;