chore: extend migration_v6.md docs

[inomdzhon]

• caused by doc: use better variant for onChange & fix typo #6369 (поправил ё)
• related to fix(a11y): ChipsSelect and ChipsInput #6367
• поправил ссылку на Chip
• удалил дубль ChipsSelect в оглавлении

[github-actions]

👀 Docs deployed

• ✅ Styleguide
• ❌ Storybook

Commit dcc38d6

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (90afa54) 81.29% compared to head (dcc38d6) 81.29%.
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #6384   +/-   ##
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  Coverage   81.29%   81.29%           
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  Files         326      326           
  Lines       10126    10126           
  Branches     3405     3405           
=======================================
  Hits         8232     8232           
  Misses       1894     1894           

Flag	Coverage Δ
unittests	81.29% <ø> (ø)

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