Fixed description of WSTOPSIG(), added WTERMSIG(). Problem reported

by Jonathan Giddy <jon@dgs.monash.edu.au>.

Doc/lib/libos.tex

@@ -758,6 +758,11 @@ Availability: \UNIX{}.
 \end{funcdesc}
 
 \begin{funcdesc}{WSTOPSIG}{status}
+Return the signal which caused the process to stop.
+Availability: \UNIX{}.
+\end{funcdesc}
+
+\begin{funcdesc}{WTERMSIG}{status}
 Return the signal which caused the process to exit.
 Availability: \UNIX{}.
 \end{funcdesc}