docs: design rationale page and library-detail.adoc

[alandefreitas]

• Add design rationale page covering character type choices (char vs char8_t, no templates, EBCDIC), allocation
  strategy, error handling, URL validity invariant, and no IRIs
• Restore library-detail.adoc with a shorter, stable description that won't get out of sync

fix #984

[cppalliance-bot]

An automated preview of the documentation is available at https://987.url.prtest2.cppalliance.org/index.html

If more commits are pushed to the pull request, the docs will rebuild at the same URL.

2026-04-04 02:20:26 UTC

[cppalliance-bot]

GCOVR code coverage report https://987.url.prtest2.cppalliance.org/gcovr/index.html
LCOV code coverage report https://987.url.prtest2.cppalliance.org/genhtml/index.html
Coverage Diff Report https://987.url.prtest2.cppalliance.org/diff-report/index.html

Build time: 2026-04-04 02:33:12 UTC

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.11%. Comparing base (2c6cdc6) to head (66b911a).
⚠️ Report is 2 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #987   +/-   ##
========================================
  Coverage    99.11%   99.11%           
========================================
  Files          155      155           
  Lines        10094    10094           
========================================
  Hits         10005    10005           
  Misses          89       89           

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[sdarwin]

@alandefreitas

• the library-detail.adoc file should be merged to master.
• this is all a temporarily work-around. If you prefer to use README.adoc, by 1.92.0 the website should pick up README.adoc. Which leads to a question, are you happy with the stub library-detail.adoc being shown on 1.91.0? If not then why not copy over the full page?

[alandefreitas]

Thanks!

Yes. I purposefully chose a more compact summary for the website. Replicating the entire readme file on that page always felt a little weird anyway.

This new shorter version also ensures the content remains relevant over time and doesn't break the intented design they have for the website.