Update Documentation to Indicate When Outputs will be Empty

[andar1an]

Preflight Checklist

• [X] I could not find a solution in the existing issues, docs, nor discussions
• [X] I have joined the ZITADEL chat

Describe the docs your are missing or that are wrong

One example: When using PKCE, one is not returned a client secret. Unless you have gone though the UI first, you don't know this. I didn't see this in any docs, especially not in the Terraform docs.

Please indicate if there are scenarios where an output will be empty in documentation. Thanks.

Additional Context

No response

[andar1an]

Closing issue, moved on to alternate solution