docs: update resources API docs

docs/api/resources/material/get-guid.md

@@ -0,0 +1,24 @@
+# Material::GetGUID
+
+```cpp
+ResourceGUID GetGUID() const override;
+```
+
+获取材质的全局唯一标识符。
+
+**返回：** 资源 GUID
+
+**线程安全：** ✅
+
+**复杂度：** O(1)
+
+**示例：**
+
+```cpp
+ResourceHandle<Material> mat = ResourceManager::Get().Load<Material>("materials/pbr.mat");
+ResourceGUID guid = mat->GetGUID();
+```
+
+## 相关文档
+
+- [Material](material.md) - 返回类总览