Further improve 1990/jaw/shark.sh

The script now deletes the tarball in the entry's directory.

The README.md file now suggests one use the try.sh script.

1990/jaw/try.sh

@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
 
 echo "Running shark.sh:"
-sh shark.sh shark.sh README.md jaw.c > receive || exit 1
+sh shark.sh shark.sh README.md jaw.c try.sh > receive || exit 1
 echo "Done."