[schema] React to yams improvement of metadata attribute handling. * Change the way RichString is deprecated. * Add documentation about metadata attribute

#! /bin/sh -e
 
case "$1" in
    purge)
	rm -rf /etc/cubicweb.d/
	rm -rf /var/log/cubicweb/
	rm -rf /var/lib/cubicweb/
    ;;
esac
 
#DEBHELPER#
 
exit 0