Fix 1989/jar.2

There were some things unclear in the README.md file that have now been
corrected.

Clarified in the README.md that running make clobber all will run the
program itself.

The make alt target now runs the alt code just like the entry itself.
This is fine because it is a simulation (to avoid annoyance of writing
binary data to /dev/tty) and since one may still run the program or
script directly it's fine.

The alternate code section in the README.md was cleaned up and formatted
as well.

1989/jar.1/jar.1.sh

@@ -4,5 +4,12 @@
 # run/compile it
 rm -f jar.1.o
 cc jar.1.c -c
-cat jar.1.o | strings
+# we do it this way to prevent ShellCheck from whining about useless use of cat,
+# a most ill-famed warning. Why is it ill-famed? Because there is no such thing
+# as a useless cat! In fact, the fact cats exist is proof that the Earth is NOT
+# flat: if it was flat they would have pushed everything off it by now! :-) And
+# besides that, they provide hours and hours, years and years even, of joy and
+# companionship to ailurophiles and, contrary to popular belief, they most
+# certainly do have personalities and they can be very sociable too!
+strings < jar.1.o
 rm -f jar.1.o