Doc: Remove instructions for using qtdemo from examples README

The Qt Examples and Demos Launcher is not maintained anymore. Edit the
README to mention Qt Creator as the way to find and launch examples.

Task-number: QTBUG-28388
Change-Id: Ic907e2a430571a0f5b3dc1ff8582c3d296ef1682
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@digia.com>

examples/activeqt/README

@@ -3,37 +3,7 @@ have been written to provide developers with examples of the Qt API in use,
 highlight good programming practice, and showcase features found in each of
 Qt's core technologies.
 
-The example and demo launcher can be used to explore the different categories
-available. It provides an overview of each example, lets you view the
-documentation in Qt Assistant, and is able to launch examples and demos.
+Documentation for examples can be found via the Examples and Tutorials link
+in the main Qt documentation. The examples and their documentation can also
+be opened from the Examples tab of Qt Creator's Welcome mode.
 
-Documentation for examples can be found in the Tutorial and Examples section
-of the Qt documentation.
-
-
-Finding the Qt Examples and Demos launcher
-==========================================
-
-On Windows:
-
-The launcher can be accessed via the Windows Start menu. Select the menu
-entry entitled "Qt Examples and Demos" entry in the submenu containing
-the Qt tools.
-
-On Mac OS X:
-
-For the binary distribution, the qtdemo executable is installed in the
-/Developer/Applications/Qt directory. For the source distribution, it is
-installed alongside the other Qt tools on the path specified when Qt is
-configured.
-
-On Unix/Linux:
-
-The qtdemo executable is installed alongside the other Qt tools on the path
-specified when Qt is configured.
-
-On all platforms:
-
-The source code for the launcher can be found in the demos/qtdemo directory
-in the Qt package. This example is built at the same time as the Qt libraries,
-tools, examples, and demonstrations.