docs: update RHI API docs

docs/api/rhi/d3d12/command-list/copy-buffer.md

@@ -13,8 +13,18 @@ void CopyBuffer(ID3D12Resource* dst, uint64_t dstOffset, ID3D12Resource* src, ui
 - `srcOffset` - 源偏移
 - `size` - 复制大小
 
-**复杂度：** O(n)
+**复杂度：** O(n)，n 为复制数据量
+
+**示例：**
+
+```cpp
+ID3D12Resource* srcBuffer = /* 源缓冲区 */;
+ID3D12Resource* dstBuffer = /* 目标缓冲区 */;
+cmdList.CopyBuffer(dstBuffer, 0, srcBuffer, 0, 1024);
+```
 
 ## 相关文档
 
 - [D3D12CommandList 总览](command-list.md) - 返回类总览
+- [CopyResource](copy-resource.md) - 复制整个资源
+- [CopyTexture](copy-texture.md) - 复制纹理数据