kubeadm-upgrade: add the 'node [config]' sub-command (#8960)

- Add includes for the generated pages
- Include placeholder generated pages

content/en/docs/reference/setup-tools/kubeadm/generated/kubeadm_upgrade_node.md

@@ -0,0 +1,6 @@
+
+PLACEHOLDER FILE UNTIL WE GENERATE THE REAL THING. DO NOT REMOVE FROM 1.11 DOCS BRANCH
+
+### Synopsis
+
+Upgrade commands for a node in the cluster. Currently only supports upgrading the configuration, not the kubelet itself.

content/en/docs/reference/setup-tools/kubeadm/generated/kubeadm_upgrade_node_config.md

@@ -0,0 +1,6 @@
+
+PLACEHOLDER FILE UNTIL WE GENERATE THE REAL THING. DO NOT REMOVE FROM 1.11 DOCS BRANCH
+
+### Synopsis
+
+Downloads the kubelet configuration from the cluster ConfigMap kubelet-config-1.X, where X is the minor version of the kubelet.

content/en/docs/reference/setup-tools/kubeadm/kubeadm-upgrade.md

@@ -38,6 +38,9 @@ applied to static pod manifests.
 ## kubeadm upgrade diff {#cmd-upgrade-diff}
 {{< include "generated/kubeadm_upgrade_diff.md" >}}
 
+## kubeadm upgrade node config {#cmd-upgrade-node-config}
+{{< include "generated/kubeadm_upgrade_node_config.md" >}}
+
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