[AIRFLOW-XXX] Add PayFit to the users list in README (apache#5927)

And update old username

README.md

@@ -247,7 +247,7 @@ Currently **officially** using Airflow:
 1. [Gusto](https://gusto.com) [[@frankhsu](https://github.com/frankhsu)]
 1. [Handshake](https://joinhandshake.com/) [[@mhickman](https://github.com/mhickman)]
 1. [Handy](http://www.handy.com/careers/73115?gh_jid=73115&gh_src=o5qcxn) [[@marcintustin](https://github.com/marcintustin) / [@mtustin-handy](https://github.com/mtustin-handy)]
-1. [happn](https://www.happn.com) [[@PierreCORBEL](https://github.com/PierreCORBEL)]
+1. [happn](https://www.happn.com) [[@pcorbel](https://github.com/pcorbel)]
 1. [HAVAN](https://www.havan.com.br) [[@botbiz](https://github.com/botbiz)]
 1. [HBC Digital](http://tech.hbc.com) [[@tmccartan](https://github.com/tmccartan) & [@dmateusp](https://github.com/dmateusp)]
 1. [HBO](http://www.hbo.com/)[[@yiwang](https://github.com/yiwang)]
@@ -323,6 +323,7 @@ Currently **officially** using Airflow:
 1. [Pagar.me](https://pagar.me/) [[@pagarme](https://github.com/pagarme)]
 1. [Palo Alto Networks](https://www.paloaltonetworks.com/) [[@PaloAltoNetworks](https://github.com/PaloAltoNetworks)]
 1. [Pandora Media](https://www.pandora.com/) [[@Acehaidrey](https://github.com/Acehaidrey) & [@wolfier](https://github.com/wolfier)]
+1. [PayFit](https://payfit.com) [[@pcorbel](https://github.com/pcorbel)]
 1. [PAYMILL](https://www.paymill.com/) [[@paymill](https://github.com/paymill) & [@matthiashuschle](https://github.com/matthiashuschle)]
 1. [PayPal](https://www.paypal.com/) [[@r39132](https://github.com/r39132) & [@jhsenjaliya](https://github.com/jhsenjaliya)]
 1. [Pernod-Ricard](https://www.pernod-ricard.com/) [[@romain-nio](https://github.com/romain-nio)]