Add the policy addon overview video link

[mprahl]

/cc @dhaiducek

[openshift-ci[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: dhaiducek, mprahl

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Needs approval from an approver in each of these files: - ~~[OWNERS](https://github.com/open-cluster-management-io/open-cluster-management-io.github.io/blob/main/OWNERS)~~ [dhaiducek,mprahl] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment

[dhaiducek]

/unhold