Document how to use CMake for Qt Network

Add documentation on how to use a module from CMake, alongside
the existing documentation about qmake.

While at it, also remove the mentioning of the central include;
It is not something we should actively advocate anymore. Instead,
the documentation of every class gives the correct include to use.

Task-number: QTBUG-73058
Change-Id: I71ed5a62f4f0a6d868dd1f84ea39e5ac385a2fb8
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>

src/network/doc/qtnetwork.qdocconf

@@ -27,7 +27,7 @@ qhp.QtNetwork.subprojects.classes.sortPages = true
 
 tagfile                 = ../../../doc/qtnetwork/qtnetwork.tags
 
-depends                 += qtcore qtgui qtdoc qmake
+depends                 += qtcore qtgui qtdoc qmake qtcmake
 
 headerdirs  += ..
 

src/network/doc/snippets/CMakeLists.txt

@@ -0,0 +1,12 @@
+cmake_minimum_required(VERSION 3.1.0)
+
+project(network_cppsnippets)
+
+add_executable(mytarget
+    network/tcpwait.cpp
+)
+
+# ![0]
+find_package(Qt5 COMPONENTS Network REQUIRED)
+target_link_libraries(mytarget Qt5::Network)
+# ![0]

src/network/doc/snippets/code/doc_src_qtnetwork.pro

@@ -1,3 +0,0 @@
-#! [0]
-QT += network
-#! [0]

src/network/doc/snippets/network/tcpwait.cpp

@@ -48,7 +48,7 @@
 **
 ****************************************************************************/
 
-#include <QtGui>
+#include <QCoreApplication>
 #include <QTcpSocket>
 
 int main(int argv, char **args)

src/network/doc/snippets/snippets.pro

@@ -2,6 +2,8 @@ TEMPLATE = app
 
 TARGET = network_cppsnippets
 
+# ![0]
 QT += network
+# ![0]
 
 SOURCES += network/tcpwait.cpp

src/network/doc/src/qtnetwork.qdoc

@@ -34,19 +34,16 @@
     TCP/IP. Operations such as requests, cookies, and sending data over HTTP
     are handled by various C++ classes.
 
-    \section1 Getting Started
+    \include module-use.qdocinc using qt module
+    \snippet CMakeLists.txt 0
 
-    To use Qt Network classes,add this directive into the C++ files:
-    \code
-    #include <QtNetwork>
-    \endcode
+    See also the \l{Build with CMake} overview.
 
-    \if !defined(qtforpython)
-    To link against the Qt Network module, add this line to the project file:
-    \code
-    QT += network
-    \endcode
-    \endif
+    \section2 Building with qmake
+
+    Add \c network to the \c QT variable:
+
+    \snippet snippets.pro 0
 
     \section1 Articles and Guides
 
@@ -100,13 +97,6 @@
     \qtvariable network
     \brief Provides classes to make network programming easier and portable.
 
-    To include the definitions of the module's classes, use the
-    following directive:
-
-    \snippet code/doc_src_qtnetwork.cpp 1
-
-    To link against the module, add this line to your \l qmake \c
-    .pro file:
-
-    \snippet code/doc_src_qtnetwork.pro 0
+    Qt Network provides a set of APIs for programming applications that use
+    TCP/IP. See the \l{Qt Network} overview for more information.
 */