Doc: Add menu bar to Books example

Add menu bar with Help->About that contains a short description of the
example application.
Remove redundant title string between menu and application content.

Task-number: QTBUG-68652
Change-Id: I31fb386ab9c01eff86b8ed3ef274ba8cfdb0148b
Reviewed-by: Topi Reiniö <topi.reinio@qt.io>

examples/sql/books/bookwindow.cpp

@@ -136,6 +136,7 @@ BookWindow::BookWindow()
             );
 
     ui.bookTable->setCurrentIndex(model->index(0, 0));
+    createMenuBar();
 }
 
 void BookWindow::showError(const QSqlError &err)
@@ -143,3 +144,28 @@ void BookWindow::showError(const QSqlError &err)
     QMessageBox::critical(this, "Unable to initialize Database",
                 "Error initializing database: " + err.text());
 }
+
+void BookWindow::createMenuBar()
+{
+    QAction *quitAction = new QAction(tr("&Quit"), this);
+    QAction *aboutAction = new QAction(tr("&About"), this);
+    QAction *aboutQtAction = new QAction(tr("&About Qt"), this);
+
+    QMenu *fileMenu = menuBar()->addMenu(tr("&File"));
+    fileMenu->addAction(quitAction);
+
+    QMenu *helpMenu = menuBar()->addMenu(tr("&Help"));
+    helpMenu->addAction(aboutAction);
+    helpMenu->addAction(aboutQtAction);
+
+    connect(quitAction, &QAction::triggered, this, &BookWindow::close);
+    connect(aboutAction, &QAction::triggered, this, &BookWindow::about);
+    connect(aboutQtAction, &QAction::triggered, qApp, &QApplication::aboutQt);
+}
+
+void BookWindow::about()
+{
+    QMessageBox::about(this, tr("About Books"),
+            tr("<p>The <b>Books</b> example shows how to use Qt SQL classes "
+               "with a model/view framework."));
+}

examples/sql/books/bookwindow.h

@@ -63,11 +63,16 @@ class BookWindow: public QMainWindow
 public:
     BookWindow();
 
+private slots:
+    void about();
+
 private:
     void showError(const QSqlError &err);
     Ui::BookWindow ui;
     QSqlRelationalTableModel *model;
     int authorIdx, genreIdx;
+
+    void createMenuBar();
 };
 
 #endif

examples/sql/books/bookwindow.ui

@@ -33,7 +33,7 @@
     <item>
      <widget class="QGroupBox" name="groupBox">
       <property name="title">
-       <string>Books</string>
+       <string/>
       </property>
       <layout class="QVBoxLayout">
        <property name="spacing">