### 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.
ActionCommand(
        name="kerberos",
        help="Start a kerberos ticket renewer",
        func=lazy_load_command("airflow.cli.commands.kerberos_command.kerberos"),
        args=(
            ARG_PRINCIPAL,
            ARG_KEYTAB,
            ARG_PID,
            ARG_DAEMON,
            ARG_KERBEROS_ONE_TIME_MODE,
            ARG_STDOUT,
            ARG_STDERR,
            ARG_LOG_FILE,
            ARG_VERBOSE,
        ),
    ),
    ActionCommand(
        name="webserver",
        help="Start a Airflow webserver instance",
        func=lazy_load_command("airflow.cli.commands.webserver_command.webserver"),
        args=(
            ARG_PORT,
            ARG_WORKERS,
            ARG_WORKERCLASS,
            ARG_WORKER_TIMEOUT,
            ARG_HOSTNAME,
            ARG_PID,
            ARG_DAEMON,
            ARG_STDOUT,
            ARG_STDERR,