docs(#1464): fix ADR-1244 capability doc set — followable tutorials, overlay-model + install tutorial, set/fragment/runtimeCompat reference, accuracy fixes

docs/README.md

@@ -10,6 +10,8 @@ Language versions: [English](README.md) · [Português (pt-BR)](pt-BR/README.md)
 
 - [Your first project](tutorials/your-first-project.md) — install to first shipped phase, one guaranteed path
 - [Onboarding an existing codebase](tutorials/onboarding-an-existing-codebase.md) — bring GSD Core to a brownfield repo
+- [Build your first capability](tutorials/build-your-first-capability.md) — author a tiny declarative capability and watch it act in the loop
+- [Install your first capability](tutorials/install-your-first-capability.md) — install a third-party capability end-to-end: consent, verify, check for updates, remove
 
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@@ -69,6 +71,7 @@ Language versions: [English](README.md) · [Português (pt-BR)](pt-BR/README.md)
 - [Multi-agent orchestration](explanation/multi-agent-orchestration.md) — how subagents are spawned, scoped, and coordinated
 - [Security model](explanation/security-model.md) — trust boundaries, permissions, and safe automation
 - [The capability trust model](explanation/capability-trust-model.md) — why third-party capabilities are gated by consent + integrity + reversibility, not a sandbox
+- [How overlay capabilities compose](explanation/capability-overlay-model.md) — why first-party always wins and how the loader resolves precedence, conflicts, and fail-closed gates
 - [Architecture](ARCHITECTURE.md) — system architecture, agent model, and data flow
 - [Discuss modes](workflow-discuss-mode.md) — assumptions mode vs interview mode for `/gsd-discuss-phase`
 - [Context monitoring](context-monitor.md) — context window monitoring hook architecture