Fixed priority explanation comment.

Author: feilipu

examples/AnalogRead_DigitalRead/AnalogRead_DigitalRead.ino

@@ -31,7 +31,7 @@ void setup() {
     ,  (const portCHAR *)"DigitalRead"  // A name just for humans
     ,  128  // This stack size can be checked & adjusted by reading the Stack Highwater
     ,  NULL
-    ,  2  // Priority, with 1 being the highest, and 4 being the lowest.
+    ,  2  // Priority, with 3 (configMAX_PRIORITIES - 1) being the highest, and 0 being the lowest.
     ,  NULL );
 
   xTaskCreate(