Fix containers documentation discrepancies

- Remove Size() from String docs (does not exist in source, use Length())
- Remove broken links to operator+ and operator==/!= (inline functions)
- Fix string.md to correctly reference Length/Capacity/Empty instead of Size
- Add proper documentation for inline operators in string.md

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+](operator-plus.md) | 字符串连接 |
+| operator+ | 字符串连接 |
 
 ### 比较运算符
 
 | 方法 | 描述 |
 |------|------|
-| [operator==](operator-equal.md) | 判断两个字符串是否相等 |
-| [operator!=](operator-equal.md) | 判断两个字符串是否不相等 |
+| 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 |
 
 ### 字符串操作
 
@@ -62,7 +62,7 @@
 | 方法 | 描述 |
 |------|------|
 | [CStr](cstr.md) | 获取 C 字符串指针 |
-| [Length/Size/Capacity/Empty](size.md) | 获取尺寸信息 |
+| [Length/Capacity/Empty](size.md) | 获取尺寸信息 |
 | [operator[]](./operator-subscript.md) | 下标访问 |
 
 ### 容量管理