Can not easily specify errMsg when using 'some'

[doubleloop]

In the very simple sample:

data Sample = Sample { inputFiles :: [FilePath] } deriving Show

sample = Sample <$> some (strArgument (metavar "FILES..."))

main = execParser (info sample fullDesc) >>= print

it would be grate to easily specify error msg for 'some' to get msg like:

$ ./sample
sample: no input files
Usage: sample FILES...

instead of

$ ./sample
Usage: sample FILES...

[HuwCampbell]

Pull #139 add descriptions for what is missing when parsing. You're case becomes:
Missing: FILES...
Usage: sample FILES...

[HuwCampbell]

I'm satisfied that this is fixed now