Documentation incorrectly states false is an option for enable-purge-protection on keyvault create

Documentation stats that `false `is an option for the `--enable-purge-protection` switch on `az keyvault create`

[enable-purge-protection](https://docs.microsoft.com/en-us/cli/azure/keyvault?view=azure-cli-latest#az-keyvault-create-optional-parameters)

If you try this you get the following error...

`The property "enablePurgeProtection" cannot be set to false`

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#### Document Details

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* ID: 226e5769-f6c8-a480-db78-727fb96348ec
* Version Independent ID: 8ee06a2a-6eda-11be-3c8e-6ad948be207e
* Content: [az keyvault](https://docs.microsoft.com/en-us/cli/azure/keyvault?view=azure-cli-latest)
* Content Source: [latest/docs-ref-autogen/keyvault.yml](https://github.com/MicrosoftDocs/azure-docs-cli/blob/main/latest/docs-ref-autogen/keyvault.yml)
* Service: **key-vault**
* GitHub Login: @rloutlaw
* Microsoft Alias: **routlaw**