Doc: Remove info about Qt Quick Extension Plugin wizard

The wizard has been removed from Qt Creator.

Change-Id: I5f5b4e89a5bd11d766292e7fc7766ed160d7bc67
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

doc/src/projects/creator-projects-creating.qdoc

@@ -140,12 +140,6 @@
 
                 Shared or static C++ library based on qmake
 
-            \li Qt Quick 1 Extension Plugin
-
-                C++ plugin that makes it possible to offer extensions that can
-                be loaded dynamically into Qt Quick 1 applications by using the
-                QDeclarativeEngine class
-
             \li Qt Quick 2 Extension Plugin
 
                 C++ plugin that makes it possible to offer extensions that can