boards: bl654_usb: update flashing instructions

    Update flashing instructions using built-in bootloader to use latest
    version of tool for packaging and uploading images.

Signed-off-by: Matt Rodgers <[email protected]>

Author: mrodgers-witekio

boards/ezurio/bl654_usb/doc/bl654_usb.rst

@@ -106,8 +106,10 @@ The board supports programming using the built-in bootloader.
 The board is factory-programmed with a Ezurio variation of Nordic's
 open bootloader from Nordic's nRF5x SDK. With this option, you'll use
 Nordic's `nrfutil`_ program to create firmware packages supported by this
-bootloader and flash them to the device. Make sure ``nrfutil`` is installed
-before proceeding. These instructions were tested with version 6.1.0.
+bootloader and flash them to the device. Before proceeding, make sure:
+
+* ``nrfutil`` is installed.
+* The ``nrf5sdk-tools`` command is installed within ``nrfutil``.
 
 #. With the adapter plugged in, reset the board into the bootloader by pressing
    the RESET button.
@@ -132,16 +134,19 @@ before proceeding. These instructions were tested with version 6.1.0.
 
    .. code-block:: console
 
-      nrfutil pkg generate --hw-version 52 --sd-req=0x00 \
-              --application build/zephyr/zephyr.hex \
-              --application-version 1 blinky.zip
+      nrfutil nrf5sdk-tools pkg generate \
+               --hw-version 52 \
+               --sd-req=0x00 \
+               --application build/zephyr/zephyr.hex \
+               --application-version 1 \
+               blinky.zip
 
 #. Flash it onto the board. Note :file:`/dev/ttyACM0` is for Linux; it will be
    something like ``COMx`` on Windows, and something else on macOS.
 
    .. code-block:: console
 
-      nrfutil dfu usb-serial -pkg blinky.zip -p /dev/ttyACM0
+      nrfutil nrf5sdk-tools dfu usb-serial -pkg blinky.zip -p /dev/ttyACM0
 
    When this command exits, observe the blue LED on the board blinking.