### 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.
ARG_ACCESS_LOGFILE,
            ARG_ERROR_LOGFILE,
            ARG_ACCESS_LOGFORMAT,
            ARG_LOG_FILE,
            ARG_SSL_CERT,
            ARG_SSL_KEY,
            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,
            ARG_SKIP_SERVE_LOGS,
            ARG_VERBOSE,
        ),
        epilog=(
            "Signals:\n"
            "\n"
            "  - SIGUSR2: Dump a snapshot of task state being tracked by the executor.\n"
            "\n"