Extra links supported for operators coming from third-party packages:

airflow.serialization.serialized_objects.BUILTIN_OPERATOR_EXTRA_LINKS

airflow/cli/cli_parser.py
ARG_DEBUG,
        ),
    ),
    ActionCommand(
        name='scheduler',
        help="Start a scheduler instance",
        func=lazy_load_command('airflow.cli.commands.scheduler_command.scheduler'),
        args=(
            ARG_SUBDIR,
            ARG_NUM_RUNS,
            ARG_DO_PICKLE,
            ARG_PID,
            ARG_DAEMON,
            ARG_STDOUT,
            ARG_STDERR,
            ARG_LOG_FILE,
        ),
        epilog=(
            'Signals:\n'
            '\n'
            '  - SIGUSR2: Dump a snapshot of task state being tracked by the executor.\n'
            '\n'
            '    Example:\n'
            '        pkill -f -USR2 "airflow scheduler"'
        ),
    ),
    ActionCommand(
        name='version',
        help="Show the version",
        func=lazy_load_command('airflow.cli.commands.version_command.version'),