site: port the archived pubid-*/README content — ISO/IEC/PLATEAU ports, 6 missing flavor pages, construction guide - #20

Process completed with exit code 2.

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4, actions/setup-node@v4. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Summary report available at: https://github.com/pubid/pubid.github.io/actions/runs/42470635706#summary-128713251841