docs(linter): improve no-plusplus and no-irregular-whitespace rule docs

[connorshea]

Closing code blocks were missing in the examples sections of both these rules.

As you can see on the website pages here:

• https://oxc.rs/docs/guide/usage/linter/rules/eslint/no-plusplus.html#examples
• https://oxc.rs/docs/guide/usage/linter/rules/eslint/no-irregular-whitespace.html#examples

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[Copilot]

Pull Request Overview

This PR fixes a documentation formatting issue in the no_plusplus linting rule by adding a missing closing code block marker.

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[camc314]

Thank yoU!

[codspeed-hq]

CodSpeed Performance Report

Merging #14790 will not alter performance

_{Comparing connorshea:cshea/fix-noplusplus (f94a3c9) with main (d39bed0)}

Summary

✅ 4 untouched
⏩ 33 skipped¹

Footnotes

1. 33 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩