remove stale feature alert

remove stale feature alert

This old feature alert from 3.3.0 is pretty stale, so remove
if from the code because everybody has probably suppressed
it by now.

	/* Because 'Q' used to be quit... */
	if (flags.suppress_alert < FEATURE_NOTICE_VER(3,3,0))
		pline("Note: Please use #quit if you wish to exit the game.");