[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.
# -*- coding: utf-8 -*-
# copyright %(year)s %(author)s, all rights reserved.
# contact %(author-web-site)s -- mailto:%(author-email)s
#
%(long-license)s
"""%(distname)s views/forms/actions/components for web ui"""