Doc: link to best practices documentation from "QML Applications" page

Change-Id: I4a9dc4c3ac3753fcab215bf944db2a22536570b1
Reviewed-by: Paul Wicking <paul.wicking@qt.io>
Reviewed-by: Simon Hausmann <simon.hausmann@qt.io>

doc/src/qmlapp/applicationdevelopers.qdoc

@@ -194,6 +194,7 @@ QML code is used in applications.
 \list
 \li \l{Integrating QML and C++}
 \li \l{qtquick-deployment.html}{Deploying QML Applications}
+\li \l{qtquick-bestpractices.html}{Best Practices for QML and Qt Quick}
 \li \l{qtquick-performance.html}{Performance Considerations and Suggestions}
 \li \l{qtquick-internationalization.html}{Internationalization and Localization}
 \li Testing and Debugging