CI: add markdownlint + docs-check wrapper; extend link check scope

docs/README.md

@@ -0,0 +1,18 @@
+# Mission Control docs
+
+This folder is the starting point for Mission Control documentation.
+
+## Sections
+
+- [Development workflow](./03-development.md)
+- [Testing guide](./testing/README.md)
+- [Coverage policy](./coverage-policy.md)
+- [Deployment](./deployment/README.md)
+- [Production notes](./production/README.md)
+- [Troubleshooting](./troubleshooting/README.md)
+- [Gateway WebSocket protocol](./openclaw_gateway_ws.md)
+
+## Status
+
+These pages are minimal placeholders so repo-relative links stay healthy. The actual docs
+information architecture will be defined in the Docs overhaul tasks.