Make shutdown command more intuitively with syntax

[LiiNen]

This PR contains fix about missing syntax hint in #9872, which is added from Redis 7.0.

--

The point is that we cannot use ABORT with others.

ABORT cancels an ongoing shutdown and cannot be combined with other flags.

But refer to redis.io, Syntax of command SHUTDOWN is below:
SHUTDOWN [NOSAVE | SAVE] [NOW] [FORCE] [ABORT]

Now in redis-cli of unstable branch, hint of shutdown does not seem properly like below:

When using abort with other flags, of course it is syntax error, but it seems like that we can use it together.

// src/db.c

if ((abort && flags != SHUTDOWN_NOFLAGS) ||
    (flags & SHUTDOWN_NOSAVE && flags & SHUTDOWN_SAVE))
{
    /* Illegal combo. */
    addReplyErrorObject(c,shared.syntaxerr);
    return;
}

--

What have been fixed

So, I wrote this minor fix PR to let us know right syntax properly:

When using one of nosave, save, now, and force, then abort will be disappeared in hint:

Contrary, when using abort, then all of other flags will be disappeared:

If I missed naming rule of argument in src/commands/shutdown.json, then please let me know.

Best regards,

[zuiderkwast]

I believe we wrote it like that to avoid complex-looking syntax. In the docs, we described the it in text instead:

"ABORT cancels an ongoing shutdown and cannot be combined with other flags."

A that time, we didn't have the fancy auto-complete of options in redis-cli that we have now.

[LiiNen]

I have updated PR with your comment, to make it sense. Thanks for your comment.
BTW, if it is merged to unstable or to latest stable version, is it better for me to write PR also in redis-doc (https://github.com/redis/redis-doc/pulls)?

[zuiderkwast]

BTW, if it is merged to unstable or to latest stable version, is it better for me to write PR also in redis-doc (https://github.com/redis/redis-doc/pulls)?

The JSON files from Redis are used automatically by redis.io for the syntax of each command, but all the written text documentation is in redis-doc. A PR in redis-doc is always welcome if you want to improve some text.

[LiiNen]

Thanks for your reply. I'll write doc PR after merged, if needed :)

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