[morningman]

Select the five input columns together with EXPORT_SET(...) AS ans, matching the six displayed output columns. Expose the existing setup SQL so readers can create the example table before running the query.

Fixes #3879

Versions and languages: dev and 4.x, English and Chinese; 3.x has no EXPORT_SET page.

Source verification:

• Doris branch-4.0 and master test_string_function.groovy define the same 13 input rows and evaluate the same EXPORT_SET overload
• The current example output has five input columns and ans, whereas its SQL projects only one expression

Validation:

• Checked all four copies contain identical corrected SQL
• Verified existing setup data is preserved and now visible
• Checked function call against branch-4.0 and master regression source
• git diff --check

Review:

• Goal: correct the reported documentation issue; the changed content directly addresses it.
• Scope: targeted documentation edits.
• Information architecture: active version and locale counterparts inspected; archived snapshots unchanged.
• Navigation: no paths, slugs, anchors or sidebar entries changed.
• Frontend/build: no framework, styling or build-script changes.
• Validation limits: no live Doris execution or full website build performed.
• Other concerns: No additional correctness, usability, accessibility, SEO or maintainability issues found in the changed content.