Update README.md

LinkedIn

Author: lukasb1b

README.md

@@ -20,6 +20,7 @@ IDE can be downloaded for free at [https://arduino.cc](https://www.arduino.cc/en
 -  Follow us on [Twitter](https://twitter.com/arduino)
 -  Explore our [Instagram](https://www.instagram.com/arduino.cc/)
 -  Hit the Subscribe button at [Youtube](https://www.youtube.com/c/arduino)
+-  Visit our [LinkedIn](https://linkedin.com/company/arduino)
 -  And like us at [Facebook](https://www.facebook.com/official.arduino)
 
 ## Bug reports and technical discussions