Fix arguments for renames(); bug spotted by Oliver Andrich

<oli@rhein-zeitung.de>.

Doc/lib/libos.tex

@@ -105,7 +105,7 @@ a parent directory is not empty).  Throws an \exception{os.error}
 exception if the leaf directory could not be successfully removed.
 \end{funcdesc}
 
-\begin{funcdesc}{renames}{path}
+\begin{funcdesc}{renames}{old, new}
 \versionadded{1.5.2}
 Recursive directory or file renaming function.
 Works like \function{rename()}, except creation of any intermediate