Section Support for virtual hardware version 13 is removed on https://docs.openshift.com/container-platform/4.11/updating/updating-hardware-on-nodes-running-on-vsphere.html

The text says:
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You must ensure that your nodes running in vSphere are running on the hardware version supported by OpenShift Container Platform. Currently, hardware version 13 or later is supported for vSphere virtual machines in a cluster.

You can update your virtual hardware immediately or schedule an update in vCenter.

Using hardware version 13 for your cluster nodes running on vSphere is now deprecated. This version is still fully supported, but support will be removed in a future version of OpenShift Container Platform. Hardware version 15 is now the default for vSphere virtual machines in OpenShift Container Platform.
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But the release notes at https://docs.openshift.com/container-platform/4.11/release_notes/ocp-4-11-release-notes.html#ocp-4-11-removed-features-virt-hw-v13 say that support for virtual hardware version 13 is removed in OCP 4.11 and that version 15 or later is now recommended

4.11

This was already fixed in the 4.12 documentation: https://docs.openshift.com/container-platform/4.12/updating/updating-hardware-on-nodes-running-on-vsphere.html. But the same changes need to be made to the 4.11 docs (i.e., 7.0U2 instead of 6.7U3, and hardware version 15 instead of hardware version 13).