Move release website documentation out of README

[helly25]

The README now keeps release-site operations out of the project overview and ends with its license information. Detailed publication guidance lives in a dedicated document included in the versioned release website.

AG;DR

• Move the complete Release website operational documentation from README.md to docs/release-website.md.
• Remove the Release website section entirely so License is the README's final section.
• Preserve the website layout, immutability, validation, deployment, and historical backfill guidance while correcting paths relative to docs/.
• Add the new Markdown document to release-site.json, so each versioned website publishes it and validates its local links.
• Change the README license summary to state Copyright M. Boerger, the MBO Works authors and link LICENSE and NOTICE.

Validation:

• python3 -m unittest discover -s tools -p release_site_test.py (24 tests)
• focused pre-commit checks for README.md, docs/release-website.md, and release-site.json
• git diff --check

The pre-existing dirty primary checkout was left untouched; this change was made in an isolated worktree based on current origin/main.