You should place a .. versionadded: 2.2 block somewhere before you start using the new feature.

there is no such block for the other parameters, so i am unsure how to put this.

would it make sense like this?

.. versionadded: 2.1

    The host and scheme parameters are available since Symfony 2.1

.. versionadded: 2.2

    The base_url parameter is available since Symfony 2.2

if not, do you have an example somewhere in the doc that i could use as inspiration?

I think it is great, but @weaverryan has maybe another idee? You can see this blocks everywhere in the docs, a good block is 1 line (72) characters long. A good example: http://symfony.com/doc/current/book/forms.html#groups-based-on-submitted-data

ok, added exactly as proposed.

Hey David!

Thanks for the PR! I've merged this in and tweaked/f 7A6F ixed a few other things we needed in the 2.0 and 2.1 branches that we needed for the existing "new-in-2.1" features.

Thanks!