doc: release-notes: add notes for LoRa, LoRaWAN and LED

Add release notes for LoRa, LoRaWAN and LED, got these from Manivannan
on Discord.

Signed-off-by: Fabio Baltieri <fabiobaltieri@google.com>
Co-authored-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>