Convert site to Hugo (#8316)

This commit converts content and layout to use Hugo.

content/cn/includes/federation-current-state.md

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+**Note:** `Federation V1`, the current Kubernetes federation API which reuses the Kubernetes API 
+resources 'as is', is currently considered alpha for many of its features, and there is no clear
+path to evolve the API to GA. However, there is a `Federation V2` effort in progress to implement
+a dedicated federation API apart from the Kubernetes API. The details can be found at
+[sig-multicluster community page](https://github.com/kubernetes/community/tree/master/sig-multicluster).
+{: .note}
+