fixing ls/script.04.sh file

Author: shreefAhmedM

individual-shell-tools/ls/script-04.sh

@@ -21,4 +21,4 @@ echo "Second exercise (sorted oldest to newest):"
 
 # TODO: Write a command which does the same as above, but sorted in the opposite order (oldest first).
 # The output should be a list of names in this order, one per line: helper-2.txt, helper-1.txt, helper-3.txt.
-ls -1t child-directory
+ ls -1tr child-directory