Antora docs: modify dir copy step

[sdarwin]

No description provided.

[cppalliance-bot]

An automated preview of the documentation is available at https://25.buffers.prtest.cppalliance.org/libs/buffers/doc/html/index.html

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.08%. Comparing base (11de60a) to head (278ea81).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop      #25   +/-   ##
========================================
  Coverage    99.08%   99.08%           
========================================
  Files           28       28           
  Lines          766      766           
========================================
  Hits           759      759           
  Misses           7        7           

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[cppalliance-bot]

GCOVR code coverage report https://25.buffers.prtest.cppalliance.org/gcovr/index.html
LCOV code coverage report https://25.buffers.prtest.cppalliance.org/genhtml/index.html
Coverage Diff https://25.buffers.prtest.cppalliance.org/gcovr/coverage_diff.txt