Revert "remove previous suggestion to explicitly say the user to run as"

This reverts commit 30e9861785e43d2648a5490dfa5799ca4e8bf8ba.

causes:
Mar 12 16:10:23 rover crontab[3205]: (root) REPLACE (root)
Mar 12 16:11:01 rover cron[994]: (*system*team-diana-daily-reboot) RELOAD (/etc/cron.d/team-diana-daily-reboot)
Mar 12 16:11:01 rover cron[994]: Error: bad username; while reading /etc/cron.d/team-diana-daily-reboot
Mar 12 16:11:01 rover cron[994]: (*system*team-diana-daily-reboot) ERROR (Syntax error, this crontab file will be ignored)
Mar 12 16:11:01 rover cron[994]: (root) RELOAD (crontabs/root)

Conflicts:
	cron.d/daily-reboot