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/README.md

@@ -9,36 +9,45 @@ Finland
 
 ## To build:
 
+NOTE: this will run the program itself.
+
 ```sh
 make clobber all
 ```
 
+There is an alternate version with a slight difference. See [Alternate
+code](#alternate-code) below.
+
 ## To run:
 
+NOTE: this will run the program itself:
+
 ```sh
 make clobber all
 ```
 
 ### Alternate code:
 
-One may try:
+This code, which prints something slightly different, is provided as well.
 
-```
-./jar.1.sh
-```
+#### To build:
 
-Or for the original $xurce might not compile using modern compilers, try:
+NOTE: this will run the program itself.
 
 ```sh
 make clobber alt
 ```
 
-or even:
+#### To run:
+
+Alternatively, you can run it directly:
+
 
 ```sh
 ./jar.1.alt.sh
 ```
 
+
 ## Judges' remarks:
 
 On many systems the compiler will not allow you to send the object file to