docs: 更新 containers 和 threading 模块文档

- containers: 更新 string 类的多个方法文档
- threading: 更新 mutex 和 task-group 方法文档

docs/api/containers/array/begin-end.md

@@ -22,7 +22,7 @@ ConstIterator end() const;
 **示例：**
 
 ```cpp
-#include <XCEngine/Containers/Array.h>
+#include <XCEngine/Core/Containers/Array.h>
 
 XCEngine::Containers::Array<int> arr = {10, 20, 30, 40, 50};
 

docs/api/containers/array/constructor.md

@@ -28,7 +28,7 @@ Array(std::initializer_list<T> init);
 **示例：**
 
 ```cpp
-#include <XCEngine/Containers/Array.h>
+#include <XCEngine/Core/Containers/Array.h>
 
 using namespace XCEngine::Containers;