[jongos]

Summary

Applies Jon’s prepared Hex Men collection update for this repository:

• Adds The Problem and What This Does About It sections to README.md (plain-language problem/solution framing).
• Renames and expands the README’s Hex Men section to Part of the Hex Men Collection, linking the Hex Men hub and sibling projects (including Colossus).
• Updates the generated landing page (site/index.html) and site generator (tools/build_site.mjs) with matching plain-language copy and a Hex Men collection list; adds minimal CSS for the collection list and plain-language block in site/style.css.

LICENSE is unchanged (Apache-2.0, verified identical to main).

Verification

• Patch applied with git am on top of current main (no conflicts).
• node tools/build_site.mjs — site/index.html is byte-identical to the committed output.
• In-page # anchors on the landing page resolve.
• External GitHub links in the new cross-references return HTTP 200.
• node --test test.mjs passes.

Known pre-existing issue (not introduced here)

python3 tools/test_site_static.py fails on main and on this branch because site/related-work.md does not match RELATED-WORK.md. That drift predates this change and is out of scope for this PR.