Docs describe function limits and best practice

[Ayush4958]

Resolves #9105

Changes:

• Added a Best Practices section for describe() & describeElement() in contributor_docs/web_accessibility.md
• Documented TTS engine limitations regarding transliterations
• Documented macOS VoiceOver's failure to respect the lang attribute for Latin Script langs

Screenshots of the change:
NA

PR Checklist

• npm run lint passes
• Inline reference is included / updated
• Unit tests are included / updated

[Ayush4958]

hi @perminder-17 ,

PR is ready for review
take time to review

thanks ....

[kvnloo]

Thanks for landing this in contributor_docs/web_accessibility.md — that is the right file for #9105, and both requested bullets are present.

One accuracy gap vs current main (describe.js still describe(text, display) / describeElement(name, text, display); _describeHTML does not set lang):

The VoiceOver bullet talks about the HTML lang attribute as if describe() / describeElement() already emit it. They do not, until the optional lang work in #9100. #9105 is intentionally docs-ahead of that API, but the new section should say so in one clause so contributors do not think the attribute is already on the fallback/label nodes.

Suggested tightening (wording only; no API change):

• Native script: prefer “write descriptions in the language’s native script (for example Devanagari for Hindi), not a Latin transliteration.” “Native script language” is easy to misread as “whatever language the author speaks.”
• VoiceOver: keep the Update describe function limits and best practices #9105 fact (VoiceOver ignores lang, so Spanish/German/French etc. are typically read with an English voice) and add (1) current p5 does not set lang yet, and (2) Windows Narrator/NVDA do use lang once present — that is why Add lang parameter to describe functions to improve multingual capabilities for screen readers #9100 still wants the parameter. Otherwise this section reads as “lang is useless.”
• “default English voice”: VoiceOver uses the user’s system voice; Update describe function limits and best practices #9105 said “the English voice.” Safer to stay with the issue wording.

No need to tick the inline-reference / unit-test boxes for this contributor-doc change, and please do not add JSDoc lang syntax until #9100 actually lands the parameter.

Branch is behind main (mergeable_state: behind); the +7-line append should rebase cleanly.