Documentation about Tamil, Kannada and Sinhala

[jquast]

• document about Tamil, Kannada, and Sinhala differences. This is mainly
  to prevent AI from boiling water over "correcting" the differences
  between width(), wcswidth(), clip(), and wrap() -- as no terminal is
  known to render these languages, and unicode.org has not made any
  clear guidance for terminals with them, this library intentionally
  does not make an effort to "accurately measure" them.
• also note our small difference in grapheme clustering from python
  3.15's unicode 17 vs. our unicode 18

[codspeed]

Merging this PR will not alter performance

✅ 121 untouched benchmarks

---

_{Comparing jq/specfixes (dcba0dc) with master (3fbe12a)}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.49%. Comparing base (3fbe12a) to head (dcba0dc).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #278   +/-   ##
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  Coverage   87.49%   87.49%           
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  Files          41       41           
  Lines        5614     5614           
  Branches     1501     1501           
=======================================
  Hits         4912     4912           
  Misses        324      324           
  Partials      378      378           

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