Update README.md

SRF module is obsolete now

README.md

@@ -17,7 +17,7 @@ Use a Raspberry Pi Zero and a few other components to build your compact close l
   * [Keyboard]
 * 1x [**Power management aka PowerBoost**](https://www.adafruit.com/products/2465) (Power supply + Battery charger)
 * 1x [**Battery**](https://www.adafruit.com/products/354)
-* 1x [**Radio Module**](https://www.wirelessthings.net/srf-wireless-rf-radio-surface-mount)
+* 1x [**Radio Module**](https://www.wirelessthings.net/srf-wireless-rf-radio-surface-mount) *All WirelessThings Products have been discontinued*
 <br>
 *Why I am using the SRF module instead of the SliceOfRadio? Because it basically is just a breakout board of the SRF module and we can do it ourself:)*
   * 1x [**CC-Debugger**](http://www.aliexpress.com/item/CC-Debugger-CCxxxx-Bluetooth-ZIGBEE-Wireless-Emulator-Programmer-for-RF-System-on-Chips/32417465960.html?spm=2114.13010608.0.55.1gfz18) to flash the chip with a custom software