Missing docs for deprecated configuration options

[mik-laj]

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.

airflow/airflow/configuration.py

Lines 139 to 169 in 8f48f12

	deprecated_options = {
	('celery', 'worker_precheck'): ('core', 'worker_precheck'),
	('logging', 'base_log_folder'): ('core', 'base_log_folder'),
	('logging', 'remote_logging'): ('core', 'remote_logging'),
	('logging', 'remote_log_conn_id'): ('core', 'remote_log_conn_id'),
	('logging', 'remote_base_log_folder'): ('core', 'remote_base_log_folder'),
	('logging', 'encrypt_s3_logs'): ('core', 'encrypt_s3_logs'),
	('logging', 'logging_level'): ('core', 'logging_level'),
	('logging', 'fab_logging_level'): ('core', 'fab_logging_level'),
	('logging', 'logging_config_class'): ('core', 'logging_config_class'),
	('logging', 'colored_console_log'): ('core', 'colored_console_log'),
	('logging', 'colored_log_format'): ('core', 'colored_log_format'),
	('logging', 'colored_formatter_class'): ('core', 'colored_formatter_class'),
	('logging', 'log_format'): ('core', 'log_format'),
	('logging', 'simple_log_format'): ('core', 'simple_log_format'),
	('logging', 'task_log_prefix_template'): ('core', 'task_log_prefix_template'),
	('logging', 'log_filename_template'): ('core', 'log_filename_template'),
	('logging', 'log_processor_filename_template'): ('core', 'log_processor_filename_template'),
	('logging', 'dag_processor_manager_log_location'): ('core', 'dag_processor_manager_log_location'),
	('logging', 'task_log_reader'): ('core', 'task_log_reader'),
	('metrics', 'statsd_on'): ('scheduler', 'statsd_on'),
	('metrics', 'statsd_host'): ('scheduler', 'statsd_host'),
	('metrics', 'statsd_port'): ('scheduler', 'statsd_port'),
	('metrics', 'statsd_prefix'): ('scheduler', 'statsd_prefix'),
	('metrics', 'statsd_allow_list'): ('scheduler', 'statsd_allow_list'),
	('metrics', 'stat_name_handler'): ('scheduler', 'stat_name_handler'),
	('metrics', 'statsd_datadog_enabled'): ('scheduler', 'statsd_datadog_enabled'),
	('metrics', 'statsd_datadog_tags'): ('scheduler', 'statsd_datadog_tags'),
	('metrics', 'statsd_custom_client_path'): ('scheduler', 'statsd_custom_client_path'),
	('scheduler', 'parsing_processes'): ('scheduler', 'max_threads'),
	}

'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