Put some instructions how to get a fix for the CoAPthon3 bug

Hopefully some day they will release a new version and we will get rid
of this.

Author: Radoslav Gerganov

README.md

@@ -12,6 +12,10 @@ Python 3.4+ is required. Install with `pip3`:
 ```
 $ pip3 install py-air-control
 ```
+If your device is using CoAP then update the `CoAPthon3` dependency to get a fix for a known [bug](https://github.com/Tanganelli/CoAPthon3/issues/29):
+```
+$ pip install -U git+https://github.com/Tanganelli/CoAPthon3@89d5173
+```
 
 Wi-Fi setup
 ---

requirements.txt

@@ -1,2 +1,3 @@
 pycryptodomex>=3.4.7
-CoAPthon3>=1.0.1
+# see https://github.com/Tanganelli/CoAPthon3/issues/29
+CoAPthon3 @ git+https://github.com/Tanganelli/CoAPthon3@89d5173