Mention "alerting rules for core platform monitoring" in techpreview features documentation

The below doc shows how to enable techpreview features but it doesn't show anything for monitoring (especially regarding https://docs.openshift.com/container-platform/4.11/monitoring/managing-alerts.html#managing-core-platform-alerting-rules_managing-alerts):

https://docs.openshift.com/container-platform/4.11/nodes/clusters/nodes-cluster-enabling-features.html 

Concretely:

• "Managing alerting rules for core platform monitoring" should be listed after "The following Technology Preview features are enabled by this feature set"
• "Additional resources" should have a link to https://docs.openshift.com/container-platform/4.11/monitoring/managing-alerts.html#managing-core-platform-alerting-rules_managing-alerts