[AIRFLOW-XXX] Add Premise to list of companies who use Airflow (#5568)

README.md

@@ -312,6 +312,7 @@ Currently **officially** using Airflow:
 1. [PMC](https://pmc.com/) [[@andrewm4894](https://github.com/andrewm4894)]
 1. [Poshmark](https://www.poshmark.com)
 1. [Postmates](http://www.postmates.com) [[@syeoryn](https://github.com/syeoryn)]
+1. [Premise](http://www.premise.com) [[@jmccallum-premise](https://github.com/jmccallum-premise)]
 1. [Pronto Tools](http://www.prontotools.io/) [[@zkan](https://github.com/zkan) & [@mesodiar](https://github.com/mesodiar)]
 1. [Publicis Pixelpark](https://www.publicispixelpark.de/) [[@feluelle](https://github.com/feluelle)]
 1. [PubNub](https://pubnub.com) [[@jzucker2](https://github.com/jzucker2)]