[book] typos / clarifications in create-instance section Clarify that cubicweb-ctl upgrade needs to be run whenever cubicweb or a cube is upgraded. Related to #2632425.

#! /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