Add _Sidebar

_Sidebar.md

@@ -0,0 +1,19 @@
+## 🧭 Overview
+- [Introduction](introduction.md)
+- [Getting Started](getting-started.md)
+- [Roadmap](roadmap.md)
+
+## 🏗 Architecture
+- [System Architecture](architecture.md)
+
+## 🛠️ Development
+- [Build Instructions](build.md)
+
+## 🔍 Engine Details
+- [UI System](ui.md)
+- [Rendering Pipeline](rendering.md)
+- [Resource Management](resources.md)
+
+## 📖 Reference
+- [Glossary](glossary.md)
+- [FAQ](faq.md)