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
"""
        Validate that config values aren't invalid given other config values
        or system-level limitations and requirements.
        """
        is_executor_without_sqlite_support = self.get("core", "executor") not in (
            'DebugExecutor',
            'SequentialExecutor',
        )
        is_sqlite = "sqlite" in self.get('core', 'sql_alchemy_conn')
        if is_sqlite and is_executor_without_sqlite_support:
            raise AirflowConfigException(f"error: cannot use sqlite with the {self.get('core', 'executor')}")
        if is_sqlite:
            import sqlite3
            
            min_sqlite_version = '3.15.0'
            if StrictVersion(sqlite3.sqlite_version) < StrictVersion(min_sqlite_version):
                raise AirflowConfigException(f"error: cannot use sqlite version < {min_sqlite_version}")
        if self.has_option('core', 'mp_start_method'):
            mp_start_method = self.get('core', 'mp_start_method')
            start_method_options = multiprocessing.get_all_start_methods()
            if mp_start_method not in start_method_options:
                raise AirflowConfigException(
                    "mp_start_method should not be "
                    + mp_start_method
                    + ". Possible values are "
                    + ", ".join(start_method_options)
                )
    def _using_old_value(self, old, current_value):