docs: Add Metacore Games to USERS.md (argoproj#17827)

This PR adds Metacore Games to USERS.md. Metacore Games uses ArgoCD as part of our Kubernetes Platform and IDP.

Signed-off-by: Juho Syrjänen <[email protected]>

USERS.md

@@ -181,6 +181,7 @@ Currently, the following organizations are **officially** using Argo CD:
 1. [Meilleurs Agents](https://www.meilleursagents.com/)
 1. [Mercedes-Benz Tech Innovation](https://www.mercedes-benz-techinnovation.com/)
 1. [Mercedes-Benz.io](https://www.mercedes-benz.io/)
+1. [Metacore Games](https://metacoregames.com/)
 1. [Metanet](http://www.metanet.co.kr/en/)
 1. [MindSpore](https://mindspore.cn)
 1. [Mirantis](https://mirantis.com/)