docs: improve HtmlRspackPlugin docs and types

[grushetsky]

Summary

Changes:

• Fixes the description of HtmlRspackPluginOptions.meta and HtmlRspackPluginOptions.hash fields (previously these were mixed up in places).
• Improve descriptions and default values of other fields from HtmlRspackPluginOptions.
• Align the docs on HtmlRspackPluginOptions with the updated type.
• Apply other minor formatting and wording updates to HtmlRspackPlugin documentation.

Checklist

• Tests updated (or not required).
• Documentation updated (or not required).

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[chenjiahan]

Awesome! Thank you for your detailed improvement of the documentation. ❤️

[codspeed-hq]

CodSpeed Performance Report

Merging #9144 will not alter performance

_{Comparing grushetsky:fix-html-rspack-plugin-description (2070d01) with main (effe83c)}

Summary

✅ 6 untouched benchmarks