[Suggestion] Add option/support for defining placeholder text

[Andre601]

Idk how possible this is, but I would still like to suggest this here, which is a way, to register a placeholder text, which would be displayed on 1.13+ clients/servers, when doing tab-completion.

For example:
Let's assume I want to override/load the command /time which acts similar to the vanilla command, and has the sub commands add, set and querry.
I now want to add syntax to it like this:

@SubCommand("set")
@Syntax({"time", "world"}) // This would then be shown as <time> and <world>
@Completion({"#time", "#world"})
public void setTime(final CommandSender sender, final String time, World world){
    // We do stuff here
}

When we would now write /time set day (without using tab to auto-complete) would it now show <world> (or <time> <world>? I don't 100% get this stuff) above the command.

Here's an image showing what I mean using LuckPerms (Credit goes to Lucko for the image)