ENH: mapFields: command line option help

applications/utilities/preProcessing/mapFields/mapFields.C

@@ -2,7 +2,7 @@
   =========                 |
   \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
    \\    /   O peration     |
-    \\  /    A nd           | Copyright (C) 2011 OpenFOAM Foundation
+    \\  /    A nd           | Copyright (C) 2011-2013 OpenFOAM Foundation
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
 License
@@ -184,7 +184,7 @@ int main(int argc, char *argv[])
     argList::addOption
     (
         "sourceTime",
-        "scalar",
+        "scalar|'latestTime'",
         "specify the source time"
     );
     argList::addOption