Hello,

We are missing documentation on the `webserver_config.py` file. I think it is worth answering the following questions in this guide:
* What is this file?
* What is this file for?
* When and how should you edit this file?

Best regards,
Kamil Breguła
airflow/config_templates/default_webserver_config.py
#
#
#
"""Default configuration for the Airflow webserver"""
import os
from flask_appbuilder.security.manager import AUTH_DB
basedir = os.path.abspath(os.path.dirname(__file__))
WTF_CSRF_ENABLED = True
AUTH_TYPE = AUTH_DB