fix a comment to correctly use -upgradewallet

src/init.cpp

@@ -638,7 +638,7 @@ bool AppInit2()
     if (GetBoolArg("-upgradewallet", fFirstRun))
     {
         int nMaxVersion = GetArg("-upgradewallet", 0);
-        if (nMaxVersion == 0) // the -walletupgrade without argument case
+        if (nMaxVersion == 0) // the -upgradewallet without argument case
         {
             printf("Performing wallet upgrade to %i\n", FEATURE_LATEST);
             nMaxVersion = CLIENT_VERSION;