Fix markup

Doc/lib/libposixpath.tex

@@ -240,7 +240,7 @@ necessary.
 
 \begin{seealso}
   \seemodule{os}{The newer \function{os.walk()} generator supplies similar
-                 functionality and can be easier to use.
+                 functionality and can be easier to use.}
 \end{seealso}
 
 \end{funcdesc}