Docs: complete the audience-split education layer (docs/wikis/)

[hyperpolymath]

Summary

standards had no education layer beyond the QUICKSTART-*.adoc setup guides and no wiki mirror. A scaffold landed in #398 (docs/wikis/ with Users / Developers / Maintainers tracks + a machine manifest, following the k9-svc/*/docs/wikis/ pattern). This issue tracks completing it into a full learning resource — "beyond mere setup and basic run-through."

Remaining work

• Write each track's core-concept prose (replace the TODO markers in docs/wikis/{users,developers,maintainers}/index.adoc).
• Decide hosting: forge-hosted wiki (synced out from docs/wikis/) vs in-repo only.
• Add a glossary (A2ML, K9, RSR, CRG, contractile, innervation, 6a2).
• Add per-track worked examples (adopt a repo / write a Hypatia rule / cut a standards change).
• Keep the machine mirror (docs/wikis/0.2-AI-MANIFEST.a2ml) in step as tracks grow.

Refs

• docs(wikis): scaffold audience-split education layer (Users/Developers/Maintainers) #398 (scaffold PR)
• docs/wikis/README.adoc

Why

The dev/maintainer/user split exists only at quickstart depth; the deeper "engage fully with the materials" layer is scattered across EXPLAINME.adoc, the ADRs, the policies, and .claude/CLAUDE.md. This organizes it into an audience-segmented path.