### Body

The CLI:

`airflow variables set [-h] [-j] [-v] key VALUE`

https://airflow.apache.org/docs/apache-airflow/stable/cli-and-env-variables-ref.html#set_repeat1

Doesn't support adding description though column exists and we support it from Rest API:
https://airflow.apache.org/docs/apache-airflow/stable/stable-rest-api-ref.html#operation/post_variables

**The Task:**

Allow to set description from cli command

### Committer

- [X] I acknowledge that I am a maintainer/committer of the Apache Airflow project.
"""ClI command with subcommands."""
    name: str
    help: str
    subcommands: Iterable
    description: str | None = None
    epilog: str | None = None
CLICommand = Union[ActionCommand, GroupCommand]
DAGS_COMMANDS = (
    ActionCommand(
        name="details",
        help="Get DAG details given a DAG id",
        func=lazy_load_command("airflow.cli.commands.dag_command.dag_details"),
        args=(ARG_DAG_ID, ARG_OUTPUT, ARG_VERBOSE),
    ),
    ActionCommand(
        name="list",
        help="List all the DAGs",
        func=lazy_load_command("airflow.cli.commands.dag_command.dag_list_dags"),
        args=(ARG_SUBDIR, ARG_OUTPUT, ARG_VERBOSE),
    ),
    ActionCommand(
        name="list-import-errors",
        help="List all the DAGs that have import errors",
        func=lazy_load_command("airflow.cli.commands.dag_command.dag_list_import_errors"),
        args=(ARG_SUBDIR, ARG_OUTPUT, ARG_VERBOSE),
    ),
    ActionCommand(
        name="report",
        help="Show DagBag loading report",
        func=lazy_load_command("airflow.cli.commands.dag_command.dag_report"),