Add help dialog

mainwindow.cpp

@@ -159,6 +159,7 @@ MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent)
     menuBar()->addMenu(dockMenu);
 
     QMenu *helpMenu = menuBar()->addMenu(tr("Help"));
+    helpMenu->addAction(tr("Help"), [this]{ HelpDialog help(this); help.exec(); }, QKeySequence::HelpContents);
     helpMenu->addAction(tr("About Tenmon"), [this]{ About about(this); about.exec(); });
     helpMenu->addAction(tr("About Qt"), [this](){ QMessageBox::aboutQt(this); });