refactor i18n yaml to prevent overwriting parent non-English YAML wit…

[opoudjis]

…h local English file: metanorma/isodoc#549

Metanorma PR checklist

• Breaking changes (list related PRs)
• Documentation update required (create task for this)
• External dependency introduced (documentation update need)
• Gem with native library introduced

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (137edfd) 97.59% compared to head (4a0956d) 97.59%.
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #219   +/-   ##
=======================================
  Coverage   97.59%   97.59%           
=======================================
  Files          16       16           
  Lines         582      582           
=======================================
  Hits          568      568           
  Misses         14       14           

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