**Description**
In the trigger page, there is a text area to enter (optional) conf json. It would be great if a sample JSON can be provided programatically while defining DAG

**Use case / motivation**

This will improve usability of the UI that triggers a DAG

airflow/www/views.py
"""Base View to set Airflow related properties"""
    from airflow import macros
    route_base = ''
    
    extra_args = {
        'macros': macros,
    }
    def render_template(self, *args, **kwargs):
        return super().render_template(
            *args,
            
            scheduler_job=lazy_object_proxy.Proxy(SchedulerJob.most_recent_job),
            **kwargs,
        )
class Airflow(AirflowBaseView):  
    """Main Airflow application."""
    @expose('/health')
    def health(self):