kubeadm: add a caution about certs in HA document (#12407)

* kubeadm: add a caution about certs in HA document * Update content/en/docs/setup/independent/high-availability.md Co-Authored-By: neolit123 <neolit123@gmail.com>
kubernetes · Jan 29, 2019 · a7792a6 · a7792a6
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commit a7792a6
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diff --git a/content/en/docs/setup/independent/high-availability.md b/content/en/docs/setup/independent/high-availability.md
@@ -223,6 +223,12 @@ SSH is required if you want to control all nodes from a single machine.
     done
     ```
 
+{{< caution >}}
+Copy only the certificates in the above list. kubeadm will take care of generating the rest of the certificates
+with the required SANs for the joining control-plane instances. If you copy all the certificates by mistake,
+the creation of additional nodes could fail due to a lack of required SANs.
+{{< /caution >}}
+
 ### Steps for the rest of the control plane nodes
 
 1.  Move the files created by the previous step where `scp` was used: