docs: Added CloudSeeds as one of the users for argo (argoproj#4553)

Signed-off-by: Lennart Kindermann <lennart.kindermann@cloudseeds.de>
Signed-off-by: Alex Capras <alexcapras@gmail.com>

USERS.md

@@ -24,6 +24,7 @@ Currently, the following organizations are **officially** using Argo Workflows:
 1. [Capital One](https://www.capitalone.com/tech/)
 1. [CarTrack](https://www.cartrack.com/)
 1. [CCRi](https://www.ccri.com/)
+1. [CloudSeeds](https://www.cloudseeds.de/)
 1. [Codec](https://www.codec.ai/)
 1. [Commodus Tech](https://www.commodus.tech)
 1. [Concierge Render](https://www.conciergerender.com)