Update PHP examples to reflect changes as of 2.2

[wouterj]

The Routing component had a lot of deprecations in 2.2. The PHP examples of the configuration blocks aren't updated to follow these changes.

Example:

.. configuration-block::

    .. ...

    .. code-block:: php

        // ...
        $collection->addCollection($loader->import("..."), '/admin');

Should become:

.. configuration-block::

    .. ...

    .. code-block:: php

        // ...
        $acmeHello = $loader->import("...");
        $acmeHello->setPrefix('/admin');
        $collection->addCollection($acmeHello);

Please note that the first change, the change of the routing option names, is already fixed in the documetation.