We need to add a warning to 3.0 installation documentation about potential conflicts with 2.6.

Before creating Istio CR we should add:

Running OpenShift Service Mesh 3 and OpenShift Service Mesh 2 in one cluster will cause conflicts unless configured correctly. Make sure you are not running OpenShift Service Mesh 2 on your cluster before proceeding. See [migration guide] if you are migrating from OpenShift Service Mesh 2.