diff --git a/Readme.md b/Readme.md
index a007e0c..76076e9 100644
--- a/Readme.md
+++ b/Readme.md
@@ -13,6 +13,7 @@
     - ```/M2Ext/M2Ext.ino``` - main, actual version
     - ```/M2Ext/icons.cpp``` - icons in bitmap for GUI
     - ```/M2Ext/flows.json``` - Node-red flow exported via json. Uses Node-red Dashboard extension
+- **Documentation**: https://docs.google.com/document/d/14M0UXB10LWmCGuYbZptHsV5nLe2JfVq7LQR3fZIQFcA/edit?usp=sharing
 ## DEVICES
 - 2x M5Stack Core2 (https://shop.m5stack.com/products/m5stack-core2-esp32-iot-development-kit)
 - NeuroSky MindWave Mobile 2 (https://store.neurosky.com/pages/mindwave)