Use customized caption "Select Fixed With Font" for the KFontDialog

The idea is to give users better hint that Konsole requires fixed-width font,
so only valid fixed-width fonts are listed. That should help reducing the
common question: "Why font <xyz> is not listed in konsole?"

src/EditProfileDialog.cpp

@@ -1153,6 +1153,7 @@ void EditProfileDialog::showFontDialog()
     QFont currentFont = _ui->fontPreviewLabel->font();
 
     QWeakPointer<KFontDialog> dialog = new KFontDialog(this, KFontChooser::FixedFontsOnly);
+    dialog.data()->setCaption(i18n("Select Fixed With Font"));
     dialog.data()->setFont(currentFont, true);
 
     // TODO (hindenburg): When https://git.reviewboard.kde.org/r/103357 is