etc/user-settings.sample

adjusting to longer names in PNF_Narrowing_Engine, which was overlooked in 4106258260b3

# -*- shell-script -*- :mode=shellscript:
#
# Isabelle user settings sample -- for use in $ISABELLE_HOME_USER/etc/settings

ISABELLE_USEDIR_OPTIONS="-i true -d pdf"
ISABELLE_LOGIC=HOL