Docs: routing bullet + design doc marked implemented

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

README.md

@@ -29,8 +29,13 @@ stream.
 
 - **Content-driven pages** (`src/content.rs`, `src/app.rs`): YAML
   loaded from Gitea at boot and hot-swapped on a NATS reload signal;
-  a bad push keeps the last-good content serving. A page's `id` is
-  its URL; `qualifies` gates it to a Kanidm group.
+  a bad push keeps the last-good content serving. The `questions/`
+  tree IS the router — file paths become URLs, `_section.yaml`
+  applies criteria to a whole directory, `[name].yaml` pages serve
+  any `/dir/<value>` with the segment fed into resource keys, and
+  `requires_chain` gates a page on verifiable answer provenance next
+  to `qualifies`' Kanidm-group identity gate (see
+  `docs/design/filesystem-routes.md`).
 - **State machines as content** (`src/aggregates/`): `aggregates.yaml`
   declares each bucket's states and legal transitions; the engine
   replays a record's event history and refuses undeclared moves, with