docs: update resources API docs

docs/api/resources/material/get-memory-size.md

@@ -0,0 +1,24 @@
+# Material::GetMemorySize
+
+```cpp
+size_t GetMemorySize() const override;
+```
+
+获取材质占用的内存大小。
+
+**返回：** 内存大小（字节）
+
+**线程安全：** ✅
+
+**复杂度：** O(1)
+
+**示例：**
+
+```cpp
+ResourceHandle<Material> mat = ResourceManager::Get().Load<Material>("materials/pbr.mat");
+size_t memSize = mat->GetMemorySize();
+```
+
+## 相关文档
+
+- [Material](material.md) - 返回类总览