Added information for 'logfile' option in getProcessInfo method.

CONTRIBUTORS.txt

@@ -46,3 +46,5 @@ Contributors
 - Gary M. Josack, 2013-11-12
 
 - Márk Sági-Kazár, 2013-12-16
+
+- Gülşah Köse, 2014-07-17

docs/api.rst

@@ -296,6 +296,10 @@ Process Control
             Exit status (errorlevel) of process, or 0 if the process is still
             running.
 
+        .. describe:: logfile
+
+            Alias for "stdout_logfile".
+
         .. describe:: pid
 
             UNIX process ID (PID) of the process, or 0 if the process is not