[schema2sql] More docstrings and minor API improvements
Along the way, renamed local `column` variable to `attr` where we're NOT manipulating a DB
column name but a schema attribute.
Related to #14050899
#! /bin/sh -e
case "$1" in
remove)
if [ -x "/etc/init.d/cubicweb-ctl" ]; then
invoke-rc.d cubicweb-ctl stop || true
fi
;;
esac
#DEBHELPER#
exit 0