Update README.md

Author: Edzelf

README.md

@@ -4,4 +4,5 @@ Development for LoRa
 - RFM95 met D1 mini.docx has a wiring diagram for a LoRa mode bases on a Wemos D1 and a RFM95W tranciever.
 - STM32_LoRa contains an Arduino based sketch for the STM32F103C and a RFM95 that can send data to TTN.
 - ESP_lora_tracker contains a LoRa tracker for an ESP8288 (D1 mini) and an RFM95.
+- Nano Power System describes how to drive a LoRa end node with far less than 1 microampere current in idle mode.