fix 34425, a bug that sys.doc cannot output format

[hu-dabao]

What does this PR do?

Fix #34425

What issues does this PR fix or reference?

Previous Behavior

For more details, please check #34425
In short, salt minion1 sys.doc test.ping --out json cannot output as the format configured.

New Behavior

salt minion1 sys.doc test.ping --out json
{
    "test.ping": "\n    Used to make sure the minion is up and responding. Not an ICMP ping.\n\n    Returns ``True``.\n\n    CLI Example:\n\n        salt '*' test.ping\n    "
}

salt minion1 sys.doc test.ping
test.ping:

    Used to make sure the minion is up and responding. Not an ICMP ping.

    Returns ``True``.

    CLI Example:

        salt '*' test.ping

Tests written?

No

Please review Salt's Contributing Guide for best practices.

[cachedout]

Nice one! Thanks, @hu-dabao