Add the directives that are called to the comment above the respective resolver function

It would be helpful to see in the resolver files for which functions a directive is called.
I did not find the option of using templates or similar for the comment generation.

e.g.:
```graphql

...
type Query {
status: String! @adminRequired
}

directive @adminRequired on FIELD_DEFINITION
...
```

results in:

```golang
...
// Status is the resolver for the status field.
// @adminRequired
func (r *queryResolver) Status(ctx context.Context) (string, error) {
return "OK - GraphQL Running", nil
}
...
```