adds monitoring instructions for restore db operation

replace-db.sh

 docker exec "${PREFIX}-db" /bin/sh -c "mysqladmin --force -uroot -p${DB_ROOT_PASSWORD} drop   ${DB_NAME}"
 echo "creating ${DB_NAME}"
 docker exec "${PREFIX}-db" /bin/sh -c "mysqladmin         -uroot -p${DB_ROOT_PASSWORD} create ${DB_NAME}"
+echo "run this command in another terminal/window to monitor progress:"
+echo "docker exec -it watch -n1 ${PREFIX}-db du /var/lib/mysql/${DB_NAME}-sh"
 echo "importing ${dump_filename_path} (${PREFIX}-db/tmp/dump.sql) into ${DB_NAME}"
 docker exec "${PREFIX}-db" /bin/sh -c "mysql              -uroot -p${DB_ROOT_PASSWORD}        ${DB_NAME} < /tmp/dump.sql"