docs: Add comprehensive rehype-raw plugin documentation with TypeScript

[amansachdev]

This PR adds missing documentation for using the rehype-raw plugin with react-markdown, addressing common issues faced by developers:

• Clarifies the difference between remarkPlugins and rehypePlugins
• Provides TypeScript-specific guidance for type errors
• Adds security considerations when using rehype-raw
• Includes complete working examples

This addresses multiple user reports in issues #696 and #765 about confusion with plugin usage.

[github-actions[bot]]

Hi! It seems you removed the template which we require. Here are our templates (pick the one you want to use and click *raw* to see its source):

• pull-request-template.md

I won’t send you any further notifications about this, but I’ll keep on updating this comment, and hide it when done!

Thanks, — bb

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 100.00%. Comparing base (fda7fa5) to head (2a8bc4d).

Additional details and impacted files

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  Coverage   100.00%   100.00%           
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  Files            3         3           
  Lines         1743      1743           
  Branches       123       123           
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  Hits          1743      1743           

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