[fs.dir.entry.obs] Add linebreak to avoid overfull hbox.

Author: zygoloid

source/iostreams.tex

@@ -12982,7 +12982,7 @@
 
 \begin{itemdescr}
 \pnum
-\returns \tcode{is_regular_file(this->status())} or \tcode{is_regular_file(this->status(ec))}, respectively.
+\returns \tcode{is_regular_file(this->status())} or \tcode{is_regular_file(this->status(ec))}, respective\-ly.
 
 \pnum
 \throws As specified in~\ref{fs.err.report}.