Add pairing section (#3670)

Author: vegardinho

docs/devices/LED2109G6.md

@@ -24,6 +24,16 @@ pageClass: device-page
 
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+## Notes
+
+### Pairing
+Factory reset the light bulb ([video](https://www.youtube.com/watch?v=npxOrPxVfe0)).
+After resetting the bulb will automatically connect.
+
+While pairing, keep the bulb close to the coordinator (adapter).
+
+What works is to use (very) short “on’s” and a little bit longer “off’s”, where you kill the light as soon as the bulb shows signs of turning on.
+Start with bulb on, then off, and then 6 “on’s”, wait in the 6th ON state. (If you try play safe and go for 7 "on's" the reset sometimes fails.)
 
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