Usage of opts file about oakton

[jeremydmiller]

@lvermeulen I'm very sorry for how long this took. The opts file thingie has to be applied at the application level itself. I did push through some code just now for the 4.0 release that enables the opts file thing for apps bootstrapped by HostBuilder or WebApplication now.

[lvermeulen]

A sample command would be:

        [Description("Bla.", Name = "list-dependencies")]
	public class ListDependenciesCommand : OaktonAsyncCommand<ListDependenciesCommandInput>
	{
		public ListDependenciesCommand()
		{
			Usage("Bla.")
				.ValidFlags(
					x => x.OrganizationFlag,
					x => x.ProjectNameFlag
				);
		}

		public override async Task<bool> Execute(ListDependenciesCommandInput input)
		{
			return true;
		}
	}