Need to add proper options to generate the template from private registory using CLI

[AayushSaini101]

Describe the bug you found in AsyncAPI Docs.

The generator can fetch the private template from the registry Reference: https://www.asyncapi.com/docs/tools/generator/using-private-template

But there is no proper option in CLI commands how to use it to fetch the private templates that needs to be added https://www.asyncapi.com/docs/tools/generator/usage#asyncapi-cli

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