C++ docs: link not correctly extracted

Analogous to
https://devdocs.io/cpp/iterator/move_iterator/operator-
there is (e.g. linked in https://devdocs.io/cpp/iterator/move_iterator ) an `operator+`:
https://en.cppreference.com/w/cpp/iterator/move_iterator/operator+
but DevDocs fails to recognize it and the link there goes to a bad url:
https://en.cppreference.com/w/cpp/iterator/move_iterator/operator (i.e. missing trailing `+`)

The same issue is present e.g. for `std::reverse_iterator::operator+`, etc.

复现 C++ 的 move_iterator 文档中的错误链接，并将其与 operator- 链接以及 issue 中引用的 cppreference operator+ URL 进行比较。追踪文档链接提取的入口点；完成标准是 operator+ 链接和对应的 std::reverse_iterator::operator+ 链接保留末尾的加号，并且不再指向被截断的 URL。

由索引模型根据 Issue 内容生成。