Typo in startup.c comment

[ayoung19]

I think it's supposed to say 32.768kHz here:

ArduinoCore-samd/cores/arduino/startup.c

Line 30 in 8983308

* 1) Enable XOSC32K clock (External on-board 32.768Hz oscillator), will be used as DFLL48M reference.

I know you can figure this out from the data sheet but since this modifies the chip's defaults it should be a little more clear, it confused me at first and might save other people time.