Fix heading level of 'Try' section

It was agreed to be '## Try:' but there were many files where it was
'### Try:'. This has been corrected.

2006/monge/README.md

@@ -29,7 +29,7 @@ For more detailed information see [2006 monge in bugs.md](/bugs.md#2006-monge).
 ```
 
 
-### Try:
+## Try:
 
 ```sh
 ./monge "z = 0" "z = z*z*z + c; Abs2(z) < 4"