[H] Follow up on multi-cluster for Helm, for 4.11

Document the following items:

• List the supported multiple backends (with or without helm)
• A note on the helm section about multi-cluster support and link it to the Dev Console multi-cluster docs.

Add updates for 4.11 after this statement in the Key features section: "In OpenShift Container Platform 4.10, Helm is disabled for the Multicluster Console (Technology Preview)."

The "Multicluster Console" in this sentence will have a link to the Dev Console multi-cluster docs (or to this particular section in the 4.10 RN for now). Or you can update the link to https://deploy-preview-42063--osdocs.netlify.app/openshift-enterprise/latest/web_console/web-console.html#enable-multi-cluster-console_web-console, if ACM is released by then.