README.md: Fix instructions on deployment on Windows.

The option -quick needs to passed to windeployqt to actually scan
the .qml files.

Change-Id: Ifeb6eee4a5e16f25196721906632914eb4568081
Reviewed-by: Kai Koehne <kai.koehne@theqtcompany.com>

README.md

@@ -168,7 +168,7 @@ For detailed information on the supported compilers, see
        able to find all dependent Qt-libraries and plugins when being launched by the
        system. The easiest way to provide them for Qt 5 is to run the tool windeployqt:
 
-        windeployqt -qmldir share\qtcreator -qmldir src\plugins\qmlprofiler bin\qtcreator.exe lib\qtcreator lib\qtcreator\plugins
+        windeployqt -quick -qmldir share\qtcreator\welcomescreen -qmldir src\plugins\qmlprofiler bin\qtcreator.exe lib\qtcreator lib\qtcreator\plugins
 
 Note that unlike on Unix, you cannot overwrite executables that are running.
 Thus, if you want to work on Qt Creator using Qt Creator, you need a