Add 2020/otterness/try.sh

The .gitignore was updated but it cannot be sorted because it excludes
'*.mid' but then negates the .mid files in the repo, cvikl.mid and
entertainer.mid. These have to come after the exclusion of '*.mid'. This
is important as one might use the entry to create a .mid file that is
not done in the try script. The make clobber rule does not remove
'*.mid' files as doing so would remove the ones we want to keep.

2020/otterness/README.md

@@ -26,13 +26,12 @@ For more detailed information see [2020 otterness in bugs.md](/bugs.md#2020-otte
 ## Try:
 
 ```sh
-./prog < cvikl.mid > output.mid
-# Play output.mid with your favorite player
-
-./prog < entertainer.mid > output2.mid
-# Play output2.mid with your favorite player
+./try.sh
 ```
 
+Now play `output.mid` and `output2.mid` in an audio player that can play MIDI
+files.
+
 
 ## Judges' remarks: