build: update dependency remark-html to v15

This MR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
remark-html	14.0.1 -> 15.0.0

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Release Notes

remarkjs/remark-html

v15.0.0

Compare Source

• 995b427 Change footnotes to match how GitHub renders them
  • remove remark-footnotes if you were using that, and instead use remark-gfm
  • more options available if you switch to remark-rehype instead of this plugin remark-html

Full Changelog: https://github.com/remarkjs/remark-html/compare/14.0.1...15.0.0

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