OSSM Doc: Add a section about SMCP creation on a ROSA cluster

This doc change request is related to https://issues.redhat.com/browse/OSSM-1053

We tested OSSM 2.1.x on a ROSA cluster. The operators installation is fine.
The SMCP creation is different. We need an additional SMCP spec change when creating a SMCP on a ROSA cluster.

OCP 4.6 is a long term support version. We need to add the doc change for both SMCP creation on OCP 4.6 ROSA and on latest OCP 4.x ROSA e.g. OCP 4.9 ROSA.

Request change(s):
1. in https://docs.openshift.com/container-platform/4.9/service_mesh/v2x/ossm-create-smcp.html#ossm-control-plane-deploy-cli_ossm-create-smcp

• Add a note . The default SMCP spec will not work on a ROSA cluster. A user need to update a SMCP CR with "spec.security.identity.type=ThirdParty"

2. in https://docs.openshift.com/container-platform/4.9/service_mesh/v2x/ossm-create-smcp.html#ossm-control-plane-deploy-cli_ossm-create-smcp

• Add a section about SMCP creation on ROSA
  and provide an example version 2.1 istio-installation.yaml

apiVersion: maistra.io/v2
kind: ServiceMeshControlPlane
metadata:
  name: basic
  namespace: istio-system
spec:
  version: v2.1
  security:
    identity:
      type: ThirdParty
  tracing:
    type: Jaeger
    sampling: 10000
  policy:
    type: Istiod
  addons:
    grafana:
      enabled: true
    jaeger:
      install:
        storage:
          type: Memory
    kiali:
      enabled: true
    prometheus:
      enabled: true
  
  telemetry:
    type: Istiod