doc: release-notes: add rp2040/pico details
doc: release-notes: add rp2040/pico details

Add new RP2040 SoC and Pico board details.

Signed-off-by: Peter Johanson <4b8373d016f277527198385ba72fda0feb5da015@peterjohanson.com>

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