doc: guides: release notes: Add Raspberry Pi Pico watchdog support
doc: guides: release notes: Add Raspberry Pi Pico watchdog support

The Raspberry Pi Pico watchdog is now supported, this adds a note to
the release notes with this information.

Signed-off-by: Jamie McCrae <ded982e702e07bb7b6effafdc353db3fe172c83f@helper3000.net>

galak/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,finikorg/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,galak/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr