How do I link a variable group programmatically to keyvault?

I can do it through the Azure Portal, but I can't figure out how to do it using the cli. I would expect the create and update commands here to enable me to do it by specifying a keyvault name.

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* ID: ba39ac35-94ff-5cda-dede-4834d174ee4c
* Version Independent ID: 93f1ab7d-610b-0fc4-c247-c31dd7752f60
* Content: [az pipelines variable-group](https://docs.microsoft.com/en-us/cli/azure/ext/azure-devops/pipelines/variable-group?view=azure-cli-latest&source=docs#ext-azure-devops-az-pipelines-variable-group-create)
* Content Source: [latest/docs-ref-autogen/ext/azure-devops/pipelines/variable-group.yml](https://github.com/MicrosoftDocs/azure-docs-cli/blob/live/latest/docs-ref-autogen/ext/azure-devops/pipelines/variable-group.yml)
* GitHub Login: @rloutlaw
* Microsoft Alias: **routlaw**