[cw-ctl] fix help message for schemadiff In global help (closes #2888538) The leading space make it appears on multiple line. The help content is a bit improved in the process.

#! /bin/sh -e
#

if [ "$1" = remove -o "$1" = upgrade ]; then
  if which install-docs >/dev/null 2>&1; then
    install-docs -r cubicweb-doc
  fi
fi

#DEBHELPER#

exit 0