DemoBrowser: Do not mention QtWebKit in description

WebEngine should stand on it's own by now. It is also
arguably misleading to mention the word "WebKit" so
prominently.

Change-Id: Ibd1c98b12f5832d047e553098d6703699acf27d8
Reviewed-by: Joerg Bornemann <joerg.bornemann@theqtcompany.com>

examples/webenginewidgets/demobrowser/doc/src/demobrowser.qdoc

@@ -29,7 +29,7 @@
     \example demobrowser
     \title WebEngine Demo Browser Example
     \ingroup webengine-widgetexamples
-    \brief The QtWebKit browser example ported to use QtWebEngine
+    \brief A demo browser based on Qt WebEngine Widgets
 
     The Demo Browser example shows the \l{Qt WebEngine Widgets} module in action,
     providing a little Web browser application with support for tabs.