Include SIG headers in the duplicate notes section

[marpaia]

Consider the output from the following command:

./release-notes -start-sha=ad2ed0e7dfe1ac914e6d1ecd369d57111fd365c6 -end-sha=94e59f1636a8f8b1566ef35180519d4de5586b79

New Features

• Registers volume topology information reported by a node-level Container Storage Interface (CSI) driver. This enables Kubernetes support of CSI topology mechanisms. (#67684, @verult) Courtesy of SIG API Machinery, SIG Node, SIG Storage, and SIG Testing
• Bump addon-manager to v8.7 (#68299, @MrHohn) Courtesy of SIG Cluster Lifecycle, and SIG Testing

Notes From Multiple SIGs

SIG API Machinery, and SIG Autoscaling

• kube-controller-manager: use informer cache instead of active pod gets in HPA controller (#68241, @krzysztof-jastrzebski)

SIG Azure, and SIG Cloud Provider

• Support NodeShutdown taint for azure (#68033, @yastij)

SIG Apps, SIG Scheduling, and SIG Testing

• If TaintNodesByCondition is enabled, add node.kubernetes.io/unschedulable and node.kubernetes.io/network-unavailable automatically to DaemonSet pods. (#64954, @k82cn)

Notes from Individual SIGs

SIG Apps

• Let service controller retry creating load balancer when persistUpdate failed due to conflict. (#68087, @grayluck)

SIG Cloud Provider

• Deprecate cloudstack and ovirt controllers (#68199, @dims)

SIG Cluster Lifecycle

• kubeadm: added phase command "alpha phase kubelet config annotate-cri" (#68449, @fabriziopandini)
• External CAs can now be used for kubeadm with only a certificate, as long as all required certificates already exist. (#68296, @liztio)

SIG Node

• add missing LastTransitionTime of ContainerReady condition (#64867, @dixudx)

[onyiny-ang]

LGTM 👍 I think this will improve readability significantly.