At the moment there is several different uris in our docs and at symfony.

quick grep of docs:
/Users/robo/dev/php/Doctrine/doctrine-mapping.xsd
http://doctrine-project.org/schemas/orm/doctrine-mapping.xsd
https://raw.github.com/doctrine/doctrine2/master/doctrine-mapping.xsd

If believe we agree on one way and fix the docs.

@Ocramius have suggested to use vendor