add text column to explain what the variable is used for

same as https://github.com/apache/airflow/issues/10840 just for Variables.


airflow/www/views.py
"""Show Circles on screen for any error in the Webserver"""
    return (
        render_template(
            'airflow/circles.html',
            hostname=socket.getfqdn()
            if conf.getboolean('webserver', 'EXPOSE_HOSTNAME', fallback=True)  
            else 'redact',
        ),
        404,
    )
def show_traceback(error):  
    """Show Traceback for a given error"""
    return (
        render_template(
            'airflow/traceback.html',  
            python_version=sys.version.split(" ")[0],
            airflow_version=version,
            hostname=socket.getfqdn()
            if conf.getboolean('webserver', 'EXPOSE_HOSTNAME', fallback=True)
            else 'redact',
            info=traceback.format_exc()
            if conf.getboolean('webserver', 'EXPOSE_STACKTRACE', fallback=True)
            else 'Error! Please contact server admin.',
        ),
        500,
    )
class AirflowBaseView(BaseView):