fix(metadata): add missing void and iterable types to builtin map

[moshams272]

Description

While generating docs using doc-kit, native types like void and Iterable failed to resolve to their MDN references because they were missing from the builtin.json map. This PR adds them so they resolve correctly across projects using doc-kit.

Validation

Add tests for them in transformers.mjs.

Related Issues

None

Check List

• I have read the Contributing Guidelines and made commit messages that follow the guideline.
• I have run node --run test and all tests passed.
• I have check code formatting with node --run format & node --run lint.
• I've covered new added functionality with unit tests if necessary.

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Project	Deployment	Actions	Updated (UTC)
api-docs-tooling	Ready	Preview	Jun 20, 2026 9:51am

[cursor]

PR Summary

Low Risk
Data-only change to documentation link metadata plus test expectations; no runtime or security-sensitive logic is modified.

Overview
Adds iterable and void entries to builtin.json so transformTypeToReferenceLink can turn those native types into MDN links during doc generation (they previously stayed as unlinked `void` / `Iterable`).

Unit tests in transformers.test.mjs are updated to assert the new behavior: an outer-union case now uses Iterable<boolean> instead of a plain boolean, and a callback return type of void is expected to link to the void operator docs.

^{Reviewed by Cursor Bugbot for commit 1443cc9. Bugbot is set up for automated code reviews on this repo. Configure here.}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.60%. Comparing base (3ab987c) to head (1443cc9).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #848      +/-   ##
==========================================
- Coverage   84.62%   84.60%   -0.03%     
==========================================
  Files         176      176              
  Lines       15855    15858       +3     
  Branches     1411     1411              
==========================================
- Hits        13418    13417       -1     
- Misses       2427     2431       +4     
  Partials       10       10              

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