### 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.
"    Example:\n"
            '        pkill -f -USR2 "airflow scheduler"'
        ),
    ),
    ActionCommand(
        name="triggerer",
        help="Start a triggerer instance",
        func=lazy_load_command("airflow.cli.commands.triggerer_command.triggerer"),
        args=(
            ARG_PID,
            ARG_DAEMON,
            ARG_STDOUT,
            ARG_STDERR,
            ARG_LOG_FILE,
            ARG_CAPACITY,
            ARG_VERBOSE,
            ARG_SKIP_SERVE_LOGS,
        ),
    ),
    ActionCommand(
        name="dag-processor",
        help="Start a standalone Dag Processor instance",
        func=lazy_load_command("airflow.cli.commands.dag_processor_command.dag_processor"),
        args=(
            ARG_PID,
            ARG_DAEMON,
            ARG_SUBDIR,
            ARG_NUM_RUNS,
            ARG_DO_PICKLE,
            ARG_STDOUT,