Correct link in basic_ostream::flush() description

flush() "Behaves as an unformatted output function", but the link is to [ostream.formatted.reqmts]. Should link to [ostream.unformatted] like others in the same section.

Author: timsong-cpp

source/iostreams.tex

@@ -6632,7 +6632,7 @@
 
 \begin{itemdescr}
 \pnum
-\effects Behaves as an unformatted output function (as described in~\ref{ostream.formatted.reqmts}, paragraph 1).
+\effects Behaves as an unformatted output function (as described in~\ref{ostream.unformatted}, paragraph 1).
 If
 \tcode{rdbuf()}
 is not a null pointer,