Red Hat Managed Lokistack example misses to set the "serviceAccount" field

-  Red Hat Managed Lokistack example misses to set the "serviceAccount" field
- Here is the documentation link:
  https://docs.openshift.com/container-platform/4.18/observability/logging/logging-6.0/log6x-upgrading-to-6.html#red-hat-managed-lokistack:~:text=v6.0%20Forwarding%20to%20Red%20Hat%20Managed%20LokiStack

- Current example misses the field ".spec.serviceAccount: <serviceAccountName>".
-  A valid example should be like:
~~~
apiVersion: observability.openshift.io/v1
kind: ClusterLogForwarder
metadata:
  name: instance
  namespace: openshift-logging
spec:
  serviceAccount:
    name: <service_account_name>
  outputs:
  - name: default-lokistack
    type: lokiStack
    lokiStack:
      target:
        name: lokistack-dev
        namespace: openshift-logging
      authentication:
        token:
          from: serviceAccount
    tls:
      ca:
        key: service-ca.crt
        configMapName: openshift-service-ca.crt
  pipelines:
  - outputRefs:
    - default-lokistack
  - inputRefs:
    - application
    - infrastructure
~~~

Author: prithvipatil97

observability/logging/logging-6.0/log6x-upgrading-to-6.adoc

@@ -347,6 +347,8 @@ metadata:
   name: instance
   namespace: openshift-logging
 spec:
+  serviceAccount:
+    name: <service_account_name>
   outputs:
   - name: default-lokistack
     type: lokiStack