docs: Add SAP Concur (argoproj#1878)

Fixes docs: Add SAP Concur

Signed-off-by: Tomas Valasek [email protected]

Author: tvalasek

USERS.md

@@ -24,6 +24,7 @@ Organizations below are **officially** using Argo Rollouts. Please send a PR wit
 1. [Quipper](https://www.quipper.com/)
 1. [Quizlet](https://quizlet.com)
 1. [Salesforce](https://www.salesforce.com/)
+1. [SAP Concur](https://www.concur.com/)
 1. [Shipt](https://www.shipt.com/)
 1. [Skillz](https://www.skillz.com)
 1. [Spotify](https://www.spotify.com/)