Fix resource system documentation

The referred file "titlebarLeft.png" does not exist. In addition, some
resource path prefix explainations are wrong

Change-Id: I3d88e5baf6a6d1fe45b6174fc18a080d87a0779c
Reviewed-by: Jaime Resano <Jaime.RESANO-AISA@qt.io>
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>

src/corelib/doc/snippets/resource-system/application.pro

@@ -2,9 +2,9 @@ TEMPLATE = app
 
 QT += qml widgets
 
-#! [0] #! [qrc]
+#! [0]
 RESOURCES = application.qrc
-#! [0] #! [qrc]
+#! [0]
 
 #! [1]
 resources.files = \

src/corelib/doc/snippets/resource-system/mainwindow.cpp

@@ -108,9 +108,9 @@ void MainWindow::createActions()
     exitAct->setStatusTip(tr("Exit the application"));
     connect(exitAct, &QAction::triggered, this, &MainWindow::close);
 
-//! [21]
+//! [1]
     cutAct = new QAction(QIcon(":/images/cut.png"), tr("Cu&t"), this);
-//! [21]
+//! [1]
     cutAct->setShortcuts(QKeySequence::Cut);
     cutAct->setStatusTip(tr("Cut the current selection's contents to the "
                             "clipboard"));

src/corelib/doc/src/resource-system.qdoc

@@ -59,8 +59,8 @@
     the \c .qrc file.
 
     The path is also used by default to identify the file's content at runtime.
-    That is, the file \c titlebarLeft.png will be available in the resource system as
+    That is, the file \c copy.png will be available in the resource system as
-    \c{:/res/titlebarLeft.png} or \c{qrc:/res/titlebarLeft.png}.
+    \c{:/images/copy.png} or \c{qrc:/images/copy.png}.
     To override this default run-time name, see \l{Prefixes} and \l{Aliases}.
 
     \e{Qt Creator}, \e{Qt Design Studio}, \QD, and \e{Qt Visual Studio Tools}
@@ -102,16 +102,22 @@
     variable. If you add a \c .qrc file path to the variable, the listed
     resource files will be embedded into the generated library or executable:
 
-    \snippet resource-system/application.pro qrc
+    \snippet resource-system/application.pro 0
+
+    For simple applications, it is also possible to let qmake generate the
+    \c .qrc file for you, avoiding the need for an additional file to be
+    maintained:
+
+    \snippet resource-system/application.pro 1
 
     This creates a resource of several \c{.png} files, that are addressable
-    like this: \c{":/res/titlebarLeft.png"}.
+    like this: \c{":/images/copy.png"}.
 
     If the directory layout of the files you want to embed into the resource
     doesn't match the expectations of the application, you can specify
     \c{resources.base}. \c base is a path prefix that denotes the root point of
-    the file's alias. In the example above, if \c{resources.base} is set to
+    the file's alias. In the example below, if \c{resources.base} is set to
-    \c{"res"}, then \c{titlebarLeft.png} is addressable as \c{":/titlebarLeft.png"}.
+    \c{"images"}, then \c{copy.png} is addressable as \c{":/copy.png"}.
 
     \section1 Runtime API
 
@@ -120,7 +126,7 @@
     file path to QFile and QDir, but also for instance to the QIcon, QImage, and
     QPixmap constructors:
 
-    \snippet resource-system/mainwindow.cpp 21
+    \snippet resource-system/mainwindow.cpp 1
 
     The \c : prefix makes it explicit that "/images/cut.png" should be loaded
     from the Qt Resource System.
@@ -207,6 +213,11 @@
     resource file's content and metadata is then done after the compilation and
     linking phase, through another rcc call.
 
+    For qmake, this is enabled by adding \c resources_big to the \c CONFIG
+    variable:
+
+    \snippet resource-system/application.pro 2
+
     For CMake, you need to use the \l{qt_add_big_resources} function.
 
     \section2 External Resource Files