[Bug libstdc++/58341] Doc conflicts with standard on forbidden range of `result` in copy_backward()

[kristian.spangsege at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58341

--- Comment #1 from Kristian Spangsege <kristian.spangsege at gmail dot com> ---
Important related information here:
http://en.cppreference.com/w/Talk:cpp/algorithm/copy_backward