docs: correct use of nRF in board description

Signed-off-by: deadprogram <[email protected]>

Author: deadprogram

README.md

@@ -53,7 +53,7 @@ The following 40 microcontroller boards are currently supported:
 * [Adafruit Feather nRF52840 Express](https://www.adafruit.com/product/4062)
 * [Adafruit ItsyBitsy M0](https://www.adafruit.com/product/3727)
 * [Adafruit ItsyBitsy M4](https://www.adafruit.com/product/3800)
-* [Adafruit ItsyBitsy nrf52840](https://www.adafruit.com/product/4481)
+* [Adafruit ItsyBitsy nRF52840](https://www.adafruit.com/product/4481)
 * [Adafruit Metro M4 Express Airlift](https://www.adafruit.com/product/4000)
 * [Adafruit PyBadge](https://www.adafruit.com/product/4200)
 * [Adafruit PyGamer](https://www.adafruit.com/product/4242)