STYLE: add notes to some (most) command-line options

- mapFields and splitMeshRegions need more clarification

applications/utilities/surface/surfaceSplitByPatch/surfaceSplitByPatch.C

@@ -36,6 +36,11 @@ using namespace Foam;
 
 int main(int argc, char *argv[])
 {
+    argList::addNote
+    (
+        "write surface mesh regions to separate files"
+    );
+
     argList::noParallel();
     argList::validArgs.clear();
     argList::validArgs.append("input file");
@@ -104,7 +109,6 @@ int main(int argc, char *argv[])
         subSurf.write(outFile);
     }
 
-
     Info<< "End\n" << endl;
 
     return 0;