correct SA metadata

In the section above the values for `K8S_NAMESPACE` and  `KSA_NAME` are defined and the reasoning is explained
```
- `K8S_NAMESPACE`: For us following these steps here it will be `es`, but this will be the namespace where you deployed the external-secrets operator
- `KSA_NAME`: external-secrets (if you are not creating a new one to attach to the deployment)
```

Yet in the example name and namespace are both `team-a`.

docs/provider-google-secrets-manager.md

@@ -29,8 +29,8 @@ Let's assume you have created a service account correctly and attached a appropr
 apiVersion: v1
 kind: ServiceAccount
 metadata:
-  name: team-a
-  namespace: team-a
+  name: external-secrets
+  namespace: es
   annotations:
     iam.gke.io/gcp-service-account: example-team-a@my-project.iam.gserviceaccount.com
 ```