Fix another segfault in 1998/schnitzi

The program would also crash if the arg had any character that's not a
digit or if the arg had only 0s in it (it would work if it had 0
followed by a digit other than 0). In other words if it is converted to
0 it would segfault.

The bugs.md file has been updated as well to note what's also now in the
README.md file: even a relatively small number can cause a substantial
amount of lines of output. For instance the number 9 causes 771999 lines
(!!) of output.

1998/schnitzi/README.md

@@ -28,9 +28,17 @@
 	echo 324 >> data
 	./sort < data
 
-[Cody Boone Ferguson](/winners.html#Cody_Boone_Ferguson) fixed two segfaults in
+[Cody Boone Ferguson](/winners.html#Cody_Boone_Ferguson) fixed three segfaults in
 this entry. The first was caused by invalid data types. The second was triggered
-if one did not specify any arg. Thank you Cody for your assistance!
+if one did not specify any arg. The third happened if the arg was had any
+characters that were not the digits 1 - 9 (if it started with 0 it could work as
+long as another digit followed it and there were no other non-digits). Thank you
+Cody for your assistance!
+
+NOTE: the larger the number the number of lines of output can become
+substantially higher as well. Doing `./schnitzi 9` will actually print 771999
+lines!
+
 
 ## Judges' comments