Add 1990/dg/try.sh

It runs the program with a couple strings and then it feeds the source
code to the program (piped to less) as well (after showing the source
code with less).

1990/dg/README.md

@@ -15,7 +15,7 @@ echo foo bar | ./dg
 ### Try:
 
 ```sh
-echo "to C or not to C" | ./dg
+./try.sh
 ```