Update usage documentation for submit

[sfairchild]

It was discovered while discussing #724 that the documentation for exercism submit could be improved including showing optional additional files.

As a user I would like documentation showing the proper use of submit including any optional flags.

EDIT:
currently when a user enters exercism submit -h the output is

Submit your solution to an Exercism exercise.

	Call the command with the list of files you want to submit.

Usage:
   submit [flags]

Aliases:
  submit, s

Flags:
  -h, --help   help for submit

Global Flags:
      --timeout int   override the default HTTP timeout (seconds)
  -v, --verbose       verbose output

The output should be updated to

Submit your solution to an Exercism exercise.

	Call the command with the list of files you want to submit.

Usage:
   submit [flags] FILE1 [FILE2 ...]

Aliases:
  submit, s

Flags:
  -h, --help   help for submit

Global Flags:
      --timeout int   override the default HTTP timeout (seconds)
  -v, --verbose       verbose output

[kytrinyx]

Do you mean the documentation that is shown when running exercism -h?

[NobbZ]

Its exercism help submit or exercism submit -h meant here.

Its usage string is submit [flags], usually I'd read this as if we can optionally specify flags, but nothing else.

Instead we have to provide at least one file name and can provide many. Directories are not allowed (yet).

The fact that we have to provide a list of files is only mentioned in the description, but not in the usage string.

I'd expect a usage string like submit [flags] FILE1 [FILE2 ...].

[sfairchild]

Updated the original comment to make it more clear. I should have included more details

[kytrinyx]

Awesome, thanks for fleshing that out! I agree--this would be a much better experience.

[Steedalion]

Does this issue include no autocomplete file suggestions when?
exercism submit <TAB> not suggesting file. but instead --test and --comment.

[kytrinyx]

@Steedalion The autocomplete suggestions are a different problem. The relevant issue is #666 -- if you want to add more observations/suggestions, please do so there. Thanks!