Refactor unclear wording re vulnerabilities

[greydevv]

Initial checklist

• I read the support docs
• I read the contributing guide
• I agree to follow the code of conduct
• I searched issues and couldn’t find anything (or linked relevant results below)
• If applicable, I’ve added docs and tests

Description of changes

I found the wording to be confusing regarding vulnerabilities in rehype-katex and rehype-mathjax. The current wording:

A vulnerability in them could open you to a cross-site scripting (XSS) attack. See their readmes for more info.

This wording makes it seem like there already exists a vulnerability in them and to visit the readme to learn more about said vulnerability. I believe the intended meaning is to warn about potential future vulnerabilities. My proposed wording change is:

If a vulnerability were to be introduced in them, it could open you up to a cross-site scripting (XSS) attack. See their readmes for more info.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (1f9df2b) 100.00% compared to head (c77b1be) 100.00%.

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Additional details and impacted files

@@            Coverage Diff            @@
##              main       #90   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           15        15           
  Lines         1823      1823           
=========================================
  Hits          1823      1823           

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[wooorm]

Thanks!