does this not belong into the RoutingBundle? in the RoutingBundle, you can also configure the `dynamic.locales` which will activate a LocaleListener that will make routes get the locale from the first url part rather than hardcoded. besides being simpler to handle, this has the benefit that if i move '/de/xy' to '/en/xy' the locale will change - which would be the expected thing.

i think the whole _locale topic is a symfony framework topic, so we should move this sidebar over to the bundle doc.