Typo fix: added R letter that was missing in the word 'overflow'

WAITLIST.s

@@ -236,7 +236,7 @@ WAIT2		TS	WAITBANK	# BBANK OF CALLING PROGRAM.
 # NOTE THAT THIS PROGRAM SECTION IS NEVER ENTERED WHEN T-T1 G/E -1,
 # SINCE TD-T1+1 = (TD-T) + (T-T1+1), AND DELTA T = TD-T G/E +1.  (G/E
 # SYMBOL MEANS GREATER THAN OR EQUAL TO).  THUS THERE NEED BE NO CON-
-# CERN OVER A PREVIOUS OR IMMINENT OVEFLOW OF TIME3 HERE.
+# CERN OVER A PREVIOUS OR IMMINENT OVERFLOW OF TIME3 HERE.
 
 		AD	POS1/2		# WHEN TD IS NEXT, FORM QUANTITY
 		AD	POS1/2		#	1.0 - DELTA T = 1.0 - (TD - T)