Fix Asciidoc lint issues

[shai-almog]

Summary

• correct the NativeInterface type mapping table column configuration
• fix the heading level sequence in the JavaScript guide
• remove the stale Travis CI integration include from the developer guide

Testing

• not run (asciidoctor not available in environment)

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https://chatgpt.com/codex/tasks/task_e_68faffdc64148331b13b34b0104433e6

[github-actions]

Developer Guide build artifacts are available for download from this workflow run:

• Developer Guide HTML package
• Developer Guide PDF
• AsciiDoc linter report
• Vale report
• Unused image report

Developer Guide quality checks:

• AsciiDoc linter: No issues found (report)
• Vale: 18527 alert(s) (2720 errors, 6274 warnings, 9533 suggestions) (exit code 1) (report)
• Image references: 183 unused image(s) found (report)

Unused image preview:

• img/cover.png
• img/developer-guide/9-piece-tool.png
• img/developer-guide/add-style-dialog.png
• img/developer-guide/advanced-buildhints-eclipse.png
• img/developer-guide/advanced-buildhints-intellij.png
• img/developer-guide/advanced-buildhints-ios-settings.png
• img/developer-guide/advanced-buildhints-netbeans.png
• img/developer-guide/android-studio-preferences.png
• img/developer-guide/background006.jpg
• img/developer-guide/badges-1.png
• ... and 173 more