Remove documentation for QIconEnginePlugin::keys().

Method was removed in dcf3c95175.

Change-Id: I6c01ea7d329e15aec8b4ce29e8d3d5c3e784731a
Reviewed-by: Casper van Donderen <casper.vandonderen@nokia.com>

src/gui/image/qiconengineplugin.cpp

@@ -71,21 +71,11 @@ QT_BEGIN_NAMESPACE
     \sa {How to Create Qt Plugins}
 */
 
-/*!
-    \fn QStringList QIconEnginePlugin::keys() const
-
-    Returns
-
-    \sa create()
-*/
-
 /*!
     \fn QIconEngine* QIconEnginePlugin::create(const QString& filename)
 
     Creates and returns a QIconEngine object for the icon with the given
     \a filename.
-
-    \sa keys()
 */
 
 /*!