docs: relocate MIGRATION.md into docs/

Keeps every long-form doc under docs/ — only README.md remains at the
repo root. Updates the two references (README.md, docs/ROADMAP.md).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

README.md

@@ -56,7 +56,7 @@ The wizard will guide you through:
 - **Localization:** Searchable timezones and keyboard layout selection.
 
 ### Already on NixOS?
-Layer Nomarchy onto an existing 25.11 install without reformatting — see the [Migration Guide](MIGRATION.md).
+Layer Nomarchy onto an existing 25.11 install without reformatting — see the [Migration Guide](docs/MIGRATION.md).
 
 ---
 

docs/ROADMAP.md

@@ -2,7 +2,7 @@
 
 This is the mid-term plan for Nomarchy. It exists so future sessions — human or agent — can pick up work without re-deriving context. Items move from **Now** → **Next** → **Later** as priorities shift, and from any column into **Shipped** at the bottom when done. There are no dates: ship-when-ready.
 
-If you're new here, also read [`docs/STRUCTURE.md`](STRUCTURE.md) and [`docs/OPTIONS.md`](OPTIONS.md). Existing-NixOS users should also read [`MIGRATION.md`](../MIGRATION.md).
+If you're new here, also read [`docs/STRUCTURE.md`](STRUCTURE.md) and [`docs/OPTIONS.md`](OPTIONS.md). Existing-NixOS users should also read [`docs/MIGRATION.md`](MIGRATION.md).
 
 ## 1. Vision & guardrails
 
@@ -131,4 +131,4 @@ Each PR description should reference the row(s) in `docs/SCRIPTS.md` it closes,
 (Move items here when they land — keep them brief, link the commit/PR.)
 
 - _2026-04-25_ — Installer prompts for keyboard layout + locale, applies live; new `nomarchy.{system,}.formFactor` option; waybar drops battery widget on desktop; nm-applet visibility fix in default theme; live-ISO baseline keymap/locale (`a7e7fa9`).
-- _2026-04-25_ — `docs/OPTIONS.md` reference; `MIGRATION.md` linked from `README.md` (`3cb012b`, `6ef28f0`).
+- _2026-04-25_ — `docs/OPTIONS.md` reference; `docs/MIGRATION.md` linked from `README.md` (`3cb012b`, `6ef28f0`).