docs: update RHI API docs

docs/api/rhi/d3d12/fence/get-native-handle.md

@@ -0,0 +1,30 @@
+# D3D12Fence::GetNativeHandle
+
+## 函数签名
+
+```cpp
+void* GetNativeHandle() override
+```
+
+## 中文描述
+
+获取底层 D3D12 栅栏指针。
+
+## 返回值
+
+`void*` - 底层 `ID3D12Fence*` 指针
+
+## 复杂度
+
+O(1)
+
+## 示例
+
+```cpp
+ID3D12Fence* nativeFence = static_cast<ID3D12Fence*>(d3d12Fence->GetNativeHandle());
+```
+
+## 相关文档
+
+- [D3D12Fence](fence.md) - 类总览
+- [D3D12Fence::GetFence](get-fence.md) - 获取 D3D12 栅栏接口