Move docs for Laravel and Symfony

[oojacoboo]

Currently the docs for the Laravel and Symfony bundle/extensions are part of this repository and being maintained here. These need to be moved to their respective repositories, as their particulars are not known or maintained through this repository.

[oojacoboo]

A warning has been added to these doc pages in the latest version. We should allow these pages to remain in place for at least one more full version.

[oojacoboo]

Issue tickets have been opened with the Symfony bundle and Laravel implementations. As soon as their docs are implemented, the docs here need to be updated accordingly.