Remove DNT spec links, add deprecation reasoning

[Josh-Cena]

The spec links were removed in mdn/browser-compat-data#20975, so the macros are broken.

This also fixes #12912 by rewording @teoli2003's comment.

[github-actions]

Preview URLs

• /en-US/docs/Web/API/Navigator/doNotTrack
• /en-US/docs/Web/Accessibility/Seizure_disorders
• /en-US/docs/Web/HTTP/Headers/DNT
• /en-US/docs/Web/HTTP/Headers/Tk

External URLs (93)

URL: /en-US/docs/Web/Accessibility/Seizure_disorders
Title: Web accessibility for seizures and physical reactions

• https://colortutorial.design/ (1 time)
• https://colortutorial.design/hsb.html (1 time)
• https://colorusage.arc.nasa.gov/flashing.php (1 time)
• https://css-tricks.com/revisiting-prefers-reduced-motion/ (1 time)
• https://developer.chrome.com/blog/new-in-chrome-74/ (1 time)
• https://diagramcenter.org/ (1 time)
• https://drafts.csswg.org/css-color-adjust-1/ (2 times)
• https://drafts.csswg.org/cssom-view/ (2 times)
• https://drafts.csswg.org/mediaqueries-5/ (7 times)
• https://drafts.csswg.org/web-animations/ (3 times)
• https://drafts4.csswg.org/mediaqueries-5/ (2 times)
• https://ds.gpii.net/learn/accessibility-masterlist (1 time)
• https://en.wikipedia.org/wiki/Candela_per_square_metre (3 times)
• https://en.wikipedia.org/wiki/High-definition_television (1 time)
• https://en.wikipedia.org/wiki/Liquid_crystal_display (1 time)
• https://en.wikipedia.org/wiki/SRGB (1 time)
• https://en.wikipedia.org/wiki/Voxel (1 time)
• https://epilepsyontario.org/musicogenic-seizures/ (1 time)
• https://epilepsysociety.org.uk/ (1 time)
• https://epilepsysociety.org.uk/3d-films-and-virtual-reality (1 time)
• https://ezgif.com/ (1 time)
• https://gif-2-mp4.com/ (1 time)
• https://gist.github.com/zakirt/faa4a58cec5a7505b10e3686a226f285 (1 time)
• https://github.com/rubentd/gifplayer (1 time)
• Problems with WCAG 2.0 Flash Definition w3c/wcag#553 (1 time)
• WCAG 2.1 Understanding 2.3.1 - missing/vague dimension definitions w3c/wcag#585 (1 time)
• https://health.usf.edu/medicine/neurology/epilepsy (1 time)
• https://html.spec.whatwg.org/multipage/media.html (1 time)
• https://html.spec.whatwg.org/multipage/webappapis.html (1 time)
• https://knowbility.org/ (1 time)
• https://linkinghub.elsevier.com/retrieve/pii/S0960982217304062 (1 time)
• https://mimesniff.spec.whatwg.org/ (1 time)
• https://npm.runkit.com/animated-gif-detector (1 time)
• https://onlinelibrary.wiley.com/doi/epdf/10.1111/j.1528-1167.2005.31405.x (1 time)
• https://pinetools.com/brightness-contrast-image (1 time)
• https://pubmed.ncbi.nlm.nih.gov/16146438/ (3 times)
• https://pubmed.ncbi.nlm.nih.gov/20649469/ (1 time)
• https://pubmed.ncbi.nlm.nih.gov/?term=Barkley%20GL%5BAuthor%5D&cauthor=true&cauthor_uid=16146438 (1 time)
• https://pubmed.ncbi.nlm.nih.gov/?term=Epilepsy%20Foundation%20of%20America%20Working%20Group%5BCorporate%20Author%5D (1 time)
• https://pubmed.ncbi.nlm.nih.gov/?term=Erba%20G%5BAuthor%5D&cauthor=true&cauthor_uid=16146438 (1 time)
• https://pubmed.ncbi.nlm.nih.gov/?term=Fisher%20RS%5BAuthor%5D&cauthor=true&cauthor_uid=16146438 (1 time)
• https://pubmed.ncbi.nlm.nih.gov/?term=Harding%20G%5BAuthor%5D&cauthor=true&cauthor_uid=16146438 (1 time)
• https://pubmed.ncbi.nlm.nih.gov/?term=Wilkins%20AJ%5BAuthor%5D&cauthor=true&cauthor_uid=16146438 (1 time)
• https://stackoverflow.com/questions/19764018/controlling-fps-with-requestanimationframe (1 time)
• https://stackoverflow.com/questions/2385203/can-you-control-gif-animation-with-javascript (1 time)
• https://stackoverflow.com/questions/596216/formula-to-determine-perceived-brightness-of-rgb-color (1 time)
• https://trace.umd.edu/ (2 times)
• https://trace.umd.edu/peat/ (5 times)
• https://webvr.info/ (1 time)
• https://www.abilitynet.org.uk/sites/abilitynet.org.uk/files/Epilepsy%20and%20Computing%20Nov%202015.pdf (1 time)
• https://www.cedars-sinai.org/health-library/diseases-and-conditions/p/photosensitive-seizures.html (2 times)
• https://www.epilepsy.com/stories/revised-definition-epilepsy (1 time)
• https://www.epilepsy.com/stories/shedding-light-photosensitivity-one-epilepsys-most-complex-conditions-0 (4 times)
• https://www.epilepsy.com/what-is-epilepsy/seizure-triggers/photosensitivity (1 time)
• https://www.epilepsy.com/what-is-epilepsy/understanding-seizures/how-serious-are-seizures (1 time)
• https://www.hardingfpa.com (1 time)
• https://www.hardingtest.com/ (2 times)
• https://www.iana.org/assignments/media-types/media-types.xhtml (1 time)
• https://www.iso.org/obp/ui/ (1 time)
• https://www.kirupa.com/html5/toggling_animations_on_off.htm (1 time)
• https://www.npmjs.com/package/animated-gif-detector (1 time)
• https://www.pbs.org/video/university-place-the-photosensitive-epilepsy-analysis-tool-ep-429/ (1 time)
• https://www.sciencedaily.com/releases/2009/09/090925092858.htm (2 times)
• https://www.sciencedirect.com/journal/current-biology/vol/27/issue/9 (1 time)
• https://www.sciencedirect.com/science/article/pii/S0960982217304062?via%3Dihub (1 time)
• https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/retina-image (1 time)
• https://www.scientificamerican.com/article/how-the-color-red-influences-our-behavior/ (1 time)
• https://www.section508.gov/content/guide-accessible-web-design-development/ (1 time)
• https://www.smart-optometry.com/red-desaturation/ (1 time)
• https://www.techrepublic.com/forums/discussions/epilepsy-and-crt-lcd-screen-flicker/ (1 time)
• https://www.useragentman.com/blog/2017/04/02/using-peat-to-create-seizureless-web-animations/ (1 time)
• https://www.w3.org/TR/2019/WD-personalization-semantics-tools-1.0-20190711/ (1 time)
• https://www.w3.org/TR/UNDERSTANDING-WCAG20/seizure-does-not-violate.html (3 times)
• https://www.w3.org/TR/WCAG20-TECHS/C29.html (1 time)
• https://www.w3.org/TR/WCAG20-TECHS/G152.html (1 time)
• https://www.w3.org/TR/WCAG20/ (1 time)
• https://www.w3.org/TR/WCAG21/ (6 times)
• https://www.w3.org/TR/css-animations-1/ (1 time)
• https://www.w3.org/TR/css-color-3/ (1 time)
• https://www.w3.org/TR/css-transitions-1/ (1 time)
• https://www.w3.org/TR/mediaqueries-4/ (1 time)
• https://www.w3.org/TR/personalization-semantics-1.0/ (1 time)
• https://www.w3.org/TR/personalization-semantics-help-1.0/ (1 time)
• https://www.w3.org/TR/web-animations-1/ (2 times)
• https://www.w3.org/WAI/ (1 time)
• https://www.w3.org/WAI/GL/task-forces/low-vision-a11y-tf/ (1 time)
• https://www.w3.org/WAI/WCAG21/Understanding/contrast-minimum.html (1 time)
• https://www.w3.org/WAI/WCAG21/Understanding/three-flashes-or-below-threshold.html (2 times)
• https://www.w3.org/WAI/perspective-videos/contrast/ (1 time)
• https://www.w3.org/WAI/standards-guidelines/wcag/new-in-21/ (1 time)

---

URL: /en-US/docs/Web/HTTP/Headers/DNT
Title: DNT

• https://www.w3.org/TR/tracking-dnt/ (1 time) (Note! This may be a new URL 👀)

---

URL: /en-US/docs/Web/HTTP/Headers/Tk
Title: Tk

• https://www.w3.org/TR/tracking-dnt/ (1 time) (Note! This may be a new URL 👀)

---

URL: /en-US/docs/Web/API/Navigator/doNotTrack
Title: Navigator: doNotTrack property

• https://www.w3.org/TR/tracking-dnt/ (1 time) (Note! This may be a new URL 👀)

[wbamberg]

👍 thank you @Josh-Cena !