Help text generation should include options and arguments.

[DamianReeves]

There seems to be no way to print out help messages for arguments and options in bluebun.
I imagine specifying them is through Props but this is all rather unclear.

Also it would be great to be able to have support for mapping props like noBuild to an option of --no-build; I'm aware I can code the functionality in the run function, but some first class support would be nice.

Thanks for the framework.