Correct button name

- https://gitlab.com/gitlab-org/gitlab/-/merge_requests/64344
- https://gitlab.com/gitlab-org/gitlab/-/issues/334026

doc/user/project/clusters/add_existing_cluster.md

@@ -193,7 +193,7 @@ To add a Kubernetes cluster to your project, group, or instance:
         with limited permissions, the secret's namespace and project namespace may
         be the same.
-1. Select the **Create Kubernetes cluster** button.
+1. Select the **Add Kubernetes cluster** button.
 After about 10 minutes, your cluster is ready.