**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
search_columns = [
        'state',
        'dag_id',
        'task_id',
        'execution_date',
        'hostname',
        'queue',
        'pool',
        'operator',
        'start_date',
        'end_date',
    ]
    edit_columns = [
        'state',
        'dag_id',
        'task_id',
        'execution_date',
        'start_date',
        'end_date',
    ]
    edit_form = TaskInstanceEditForm
    base_order = ('job_id', 'asc')
    base_filters = [['dag_id', DagFilter, lambda: []]]
    def log_url_formatter(self):
        """Formats log URL."""
        log_url = self.get('log_url')  
        return Markup(  
            '<a href="{log_url}"><span class="material-icons" aria-hidden="true">reorder</span></a>'
        ).format(log_url=log_url)
    def duration_f(self):