Use standard pin name in attachInterrupt() table (#807)

The previous pin number 15 in the table for Nano 33 IoT was correct, but users are more familiar with the "An" pin naming style, as marked on the board silkscreen, so it's better to always use those names in the reference.

Author: per1234

Language/Functions/External Interrupts/attachInterrupt.adoc

@@ -26,7 +26,7 @@ The first parameter to `attachInterrupt()` is an interrupt number. Normally you
 |Micro, Leonardo, other 32u4-based |0, 1, 2, 3, 7
 |Zero                              |all digital pins, except 4
 |MKR Family boards                 |0, 1, 4, 5, 6, 7, 8, 9, A1, A2
-|Nano 33 IoT                       |2, 3, 9, 10, 11, 13, 15, A5, A7
+|Nano 33 IoT                       |2, 3, 9, 10, 11, 13, A1, A5, A7
 |Nano 33 BLE, Nano 33 BLE Sense    |all pins
 |Due                               |all digital pins
 |101                               |all digital pins (Only pins 2, 5, 7, 8, 10, 11, 12, 13 work with *CHANGE*)