Hello,

In Airflow 2, we've moved some configuration options to the new section. We also changed the names of some of the configuration options. This is confusing for users who are familiar with the old option and section names.  It would be great if we could add information to the documentation that points to the new name of the options.

https://github.com/apache/airflow/blob/8f48f12128e0d985c6de2603902524859fecbca8/airflow/configuration.py#L139-L169

> 'The {old} option in [{section}] has been renamed to {new}
> 'The {old_key} option in [{old_section}] has been moved to the {new_key} option in '
> '[{new_section}]

Best regards,
Kamil Breguła

airflow/configuration.py
"""Get Config option values from Secret Backend"""
    secrets_client = get_custom_secret_backend()
    if not secrets_client:
        return None
    return secrets_client.get_config(config_key)
def _read_default_config_file(file_name: str) -> Tuple[str, str]:
    templates_dir = os.path.join(os.path.dirname(__file__), 'config_templates')
    file_path = os.path.join(templates_dir, file_name)
    with open(file_path, encoding='utf-8') as config_file:
        return config_file.read(), file_path
DEFAULT_CONFIG, DEFAULT_CONFIG_FILE_PATH = _read_default_config_file('default_airflow.cfg')
TEST_CONFIG, TEST_CONFIG_FILE_PATH = _read_default_config_file('default_test.cfg')
def default_config_yaml() -> dict:
    """
    Read Airflow configs from YAML file
    :return: Python dictionary containing configs & their info
    """
    templates_dir = os.path.join(os.path.dirname(__file__), 'config_templates')
    file_path = os.path.join(templates_dir, "config.yml")
    with open(file_path) as config_file:
        return yaml.safe_load(config_file)
class AirflowConfigParser(ConfigParser):