Correct QtQml.Models \qmlmodule version.

For example, the following documentation [1] says:

Import Statement:   import QtQml.Models 2.0

This should be:

Import Statement:   import QtQml.Models 2.1

The module documentation [2] is correct, but there's no visible link to
that page from [1].

[1] http://qt-project.org/doc/qt-5/qml-qtqml-models-objectmodel.html
[2] http://qt-project.org/doc/qt-5/qtqml-models-qmlmodule.html

Change-Id: Ib2ab7b821ad7e98c20b396b26f745ee39434b7fb
Reviewed-by: Topi Reiniö <topi.reinio@digia.com>