[Docs] Specify in docs that command handler Create methods' parameters must match options

[j0shuams]

I spent a while trying to figure out why my options were not binding, even though I was doing everything the docs said to.
However, I was doing essentially what the docs said.

static async Task Main(string[] args)
{
    var rootCommand = new RootCommand
    {
      new Option
      (
         name: "--target",
         argumentType: typeof(string), 
         arity: ArgumentArity.ExactlyOne 
       )
     };

    rootCommand.Handler = CommandHandler.Create<string>(Foo);
    await rootCommand.InvokeAsync(args);            
}       
        
private static int Foo(string targetAssembly) // <-- mistake!
{
    Console.WriteLine($"--target = {targetAssembly}");
}

My mistake was just in the name of the parameter, and I didn't see this mentioned in the docs anywhere. I would like to suggest adding it to the first section of the "Model bindings" page :)

This other issue is how I figured out my problem, FWIW: #1326

[elgonzo]

This behavior has bitten many a users (me too), and the authors are already aware of the user confusion caused by this behavior (see here: #1012).

As a side note, and with respect to the code you have given in your report, you are not using (complex) model bindings. Your code just uses "simple" command handler parameter bindings, which is explained in a different section of the documentation, "Binding parameters to a command handler", which explains:

The default convention is that parameters are matched by name, so in the following example, option --an-int matches the parameter named anInt. Matching ignores hyphens (and other option prefixes, such as '/') and is case insensitive.