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

- mapFields and splitMeshRegions need more clarification

applications/utilities/preProcessing/foamUpgradeFvSolution/foamUpgradeFvSolution.C

@@ -48,8 +48,17 @@ using namespace Foam;
 
 int main(int argc, char *argv[])
 {
+    argList::addNote
+    (
+        "upgrade the syntax of system/fvSolution::solvers"
+    );
+
     argList::noParallel();
-    argList::addBoolOption("test");
+    argList::addBoolOption
+    (
+        "test",
+        "suppress writing the updated system/fvSolution file"
+    );
 
 #   include "setRootCase.H"
 #   include "createTime.H"
@@ -89,7 +98,6 @@ int main(int argc, char *argv[])
                     << (solutionDict.objectPath() + ".old") << nl;
             }
 
-
             solutionDict.writeObject
             (
                 IOstream::ASCII,