fix a few more quasi-common headers in winner README.md files

1989/jar.1/README.md

@@ -42,6 +42,7 @@ NOTE: this will run the program itself.
 make clobber alt
 ```
 
+
 ### Alternate use:
 
 Alternatively, you can run it directly:

1989/paul/README.md

@@ -38,6 +38,7 @@ could easily be added.
 make alt
 ```
 
+
 ### Alternate use:
 
 ```sh

1989/tromp/README.md

@@ -64,6 +64,7 @@ the judges' additional remarks in the author's remarks, for more details.
 make alt
 ```
 
+
 ### Alternate use:
 
 Use `tromp.alt` as you would `tromp` above.