docs: Fix containers module documentation discrepancies

- Array::SetAllocator: Remove reference to non-existent PoolAllocator class
- HashMap::SetAllocator: Remove reference to non-existent GetDefaultAllocator()
- HashMap::Copy/Move: Fix move constructor complexity (O(m_bucketCount), not O(1))
- HashMap::iterator: Remove C++20 structured bindings example
- String: Add missing links for operator+ and operator==/!=

docs/api/containers/string/string.md

@@ -37,14 +37,14 @@
 | 方法 | 描述 |
 |------|------|
 | [operator+=](operator-plus-assign.md) | 追加字符串/字符 |
-| operator+ | 字符串连接 |
+| [operator+](../string/operator-plus.md) | 字符串连接 |
 
 ### 比较运算符
 
 | 方法 | 描述 |
 |------|------|
-| operator== | 判断两个字符串是否相等 |
-| operator!= | 判断两个字符串是否不相等 |
+| [operator==](../string/operator-equal.md) | 判断两个字符串是否相等 |
+| [operator!=](../string/operator-equal.md) | 判断两个字符串是否不相等 |
 
 ### 字符串操作