Merge pull request #283836 from EllieC-Microsoft/ecreagh-add-abandoned-cluster-docs

[operator-nexus] [3.12] Add information about the behaviour of abandoned naks clusters

Author: prmerger-automator[bot]

articles/operator-nexus/reference-nexus-kubernetes-cluster-supported-versions.md

@@ -169,6 +169,10 @@ During the extended availability period for unsupported Kubernetes versions (tha
 > [!NOTE]
 > Operator Nexus relies on the releases and patches from [kubernetes](https://kubernetes.io/releases/), which is an Open Source project that only supports a sliding window of three minor versions. Operator Nexus can only guarantee [full support](#kubernetes-version-support-policy) while those versions are being serviced upstream. Since there's no more patches being produced upstream, Operator Nexus can either leave those versions unpatched or fork. Due to this limitation, extended availability doesn't support anything from relying on kubernetes upstream.
 
+### Abandoned Nexus Kubernetes clusters
+
+After the end of the extended availability period, the K8s version is completely removed from Nexus. At this point any existing Nexus Kubernetes clusters which are based on this K8s version will become abandoned. The only supported operation on abandoned clusters is deletion. Importantly, once a cluster is abandoned, upgrading to a later K8s version will not work.
+
 ## Supported `kubectl` versions
 
 You can use one minor version older or newer of `kubectl` relative to your *kube-apiserver* version, consistent with the [Kubernetes support policy for kubectl](https://kubernetes.io/docs/setup/release/version-skew-policy/#kubectl).