Deprecate the @DocumentLink annotation

It is possible now to create new content in the channel perspective by using the hst.manageContent tag. This makes the allowCreation attribute and function of the @DocumentLink annotation obsolete.

The other function of this annotation, to pick/select a document was always very poor and superseded by the functionality of the @JcrPath annotation.

This annotation should be marked as deprectated in version 12, and removed from version 13.