feat(adopters): add Sovereign Cloud Stack

Signed-off-by: Jan Schoone <jan@jass.es>

ADOPTERS.md

@@ -15,6 +15,7 @@ Feel free to open a Pull-Request to get yours listed.
 | Vendor | Qumulus | 2024 | [link](https://www.qumulus.io) | Qumulus is a cloud provider and plans to use Kamaji for it's hosted Kubernetes service |
 | End-user | sevensphere | 2023 | [link](https://www.sevensphere.io) | Sevensphere provides consulting services for end-user companies / cloud providers and uses Kamaji for designing cloud/on-premises Kubernetes-as-a-Service platform. |
 | End-user | Sicuro Tech Lab | 2024 | [link](https://sicurotechlab.it/) | Sicuro Tech Lab offers cloud infrastructure for Web Agencies and uses kamaji to provide managed k8s services. |
+| Vendor | Sovereign Cloud Stack | 2024 | [link](https://sovereigncloudstack.org) | Sovereign Cloud Stack develops a standardized cloud platform and uses Kamaji in there Kubernetes-as-a-Service reference implementation |
 | R&D | TIM | 2024 | [link](https://www.gruppotim.it) | TIM is an Italian telecommunications company using Kamaji for experimental research and development purposes. |
 | Vendor | Ænix | 2023 | [link](https://aenix.io/) | Ænix provides consulting services for cloud providers and uses Kamaji for running Kubernetes-as-a-Service in free PaaS platform [Cozystack](https://cozystack.io). |