ENH: mergeOrSplitBaffles: fix header. See #468.

applications/utilities/mesh/manipulation/mergeOrSplitBaffles/mergeOrSplitBaffles.C

@@ -35,12 +35,9 @@ Usage
     \b mergeOrSplitBaffles [OPTION]
 
     Options:
-      - \par -detect
+      - \par -detectOnly
         Detect baffles and write to faceSet duplicateFaces.
 
-      - \par -merge
-        Detect baffles and convert to internal faces.
-
       - \par -split
         Detect baffles and duplicate the points (used so the two sides
         can move independently)