[AIRFLOW-XXX] Add Zego as an Apache Airflow user

Closes apache#3224 from ruimffl/add-zego-as-user

README.md

@@ -232,6 +232,7 @@ Currently **officially** using Airflow:
 1. [Xoom](https://www.xoom.com/india/send-money) [[@gepser](https://github.com/gepser) & [@omarvides](https://github.com/omarvides)]
 1. [Yahoo!](https://www.yahoo.com/)
 1. [Zapier](https://www.zapier.com) [[@drknexus](https://github.com/drknexus) & [@statwonk](https://github.com/statwonk)]
+1. [Zego](https://www.zego.com/) [[@ruimffl](https://github.com/ruimffl)]
 1. [Zendesk](https://www.github.com/zendesk)
 1. [Zenly](https://zen.ly) [[@cerisier](https://github.com/cerisier) & [@jbdalido](https://github.com/jbdalido)]
 1. [Zymergen](https://www.zymergen.com/)