Emit directive abover header comment

[aspeddro]

./bsc ~/Desktop/learning-rescript/src/directive.res

#!/usr/bin/env node
// Generated by ReScript, PLEASE EDIT WITH CARE
'use strict';


console.log("Hello");

/*  Not a pure module */

Close #6170

[cristianoc]

We don't have the ability to do more 10.x releases.
Would you base it on master?

[aspeddro]

See #6172