Update README.md (#6063)

Add BigQuant to list of current users

README.md

@@ -159,6 +159,7 @@ Currently **officially** using Airflow:
 1. [BelugaDB](https://belugadb.com) [[@fabio-nukui](https://github.com/fabio-nukui) & [@joao-sallaberry](http://github.com/joao-sallaberry) & [@lucianoviola](https://github.com/lucianoviola) & [@tmatuki](https://github.com/tmatuki)]
 1. [Betterment](https://www.betterment.com/) [[@betterment](https://github.com/Betterment)]
 1. [Bexs Bank](https://www.bexs.com.br/en) [[@felipefb](https://github.com/felipefb) & [@ilarsen](https://github.com/ishvann)]
+1. [BigQuant](https://bigquant.com/) [[@bigquant](https://github.com/bigquant)]
 1. [BlaBlaCar](https://www.blablacar.com) [[@puckel](https://github.com/puckel) & [@wmorin](https://github.com/wmorin)]
 1. [Blacklane](https://www.blacklane.com) [[@serkef](https://github.com/serkef)]
 1. [Bloc](https://www.bloc.io) [[@dpaola2](https://github.com/dpaola2)]