`vmware-iso`: improve documentation when export configuration with `format` and `ovftool_options`

[hc-github-team-packer]

This issue was originally opened by @ba31 in https://github.com/hashicorp/packer/issues/12435 and has been migrated to this repository. The original issue description is below.

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It seems not clear how this option worked. Tried multiple way to use but always report "An argument named "format" is not expected here" . It would bbe good to update the documenation with some example how it should work ?