docs: Annotate unused parameters for structured output examples

[xtzie]

Summary

Update the README and example code to clarify that parameters are defined but not used in the examples.

Rationale

All other example snippets consistently use passed parameters. It was briefly confusing when I read the structured output snippets and had to double back to ensure they were indeed placeholder variables.

[maxisbey]

Not really needed. These are more pseudo code examples rather than production code, it doesn't make much sense to show that the params aren't used since they clearly wouldn't be with dummy data. They're there for demonstration purposes rather than actual functinoality.